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EDITOR & PUBLISHER | James M. Lawrence INTERNATIONAL PUBLISHER | Matthias Schmidt INTERNATIONAL EDITOR | Daniel Knop SENIOR ADVISORY BOARD |
CONTRIBUTING EDITORS |
PHOTOGRAPHERS |
2 5 6 8 14
ART DIRECTOR | Linda Provost
EDITOR’S PAGE by James M. Lawrence LETTERS REEF NEWS RARITIES by Inken Krause
The Partner Shrimp (Periclimines brevicarpalis) The Longfin Anthias (Pseudanthias ventralis) The Clarion Angelfish Angelfish (Holacanthus clarionensis)
TRANSLATOR | Mary Bailey
ASSOCIATE EDITORS |
LETTER FROM EUROPE by Daniel Knop
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INTERVIEW: Denise Nielsen Tackett & Larry Tackett
ASSOCIATE PUBLISHER |
EDITORIAL & BUSINESS OFFICES
CUSTOMER SERVICE ADVERTISING SALES |
BUSINESS OFFICE |
NEWSSTAND |
TRIGGERFISHES 26 PHOTO ESSAY by Daniel Knop 32 OH, THOSE TRIGGERS! by Professor Ellen Thaler 39 REEF�SAFE TRIGGERFISHES by Scott W. Michael 40 TAXONOMY of the Family Balistidae by Inken Krause TRAVEL 48 MADAGASCAR A Treasure Island in the Indian Ocean
PRINTING |
by Marlen Hundertmark and Christian Hepperger
CORAL®, The Reef & Marine Aquarium Magazine
(ISSN:1556-5769), is published bimonthly in January, March, May, July, September, and November by Reef to Rainforest Media, LLC, 140 Webster Road, PO Box 490, Shelburne, VT 05482. Periodicals postage paid at Shelburne, VT, and at additional entry offices. Subscription rates: U.S., $37 for one year. Canada, $49 for one year. Outside U.S. and Canada, $ 57 for one year. POSTMASTER: Send address changes to CORAL, PO Box 361, Williamsport, PA 17703-0361. CORAL® is a licensed edition of KORALLE Germany, Germany, ISSN:1556-5769 Natur und Tier Verlag GmbH | Muenster, Germany All rights reserved. Reproduction of any material from this issue in whole or in part is strictly prohibited. COVER: Rhinecanthus aculeatus
Photo by D. Knop
TECHNIQUE 54 BREEDING MANDARINS by Matthew W. Wittenrich 62 MANDARINS AT THE SMITHSONIAN 64 “NO RISK, NO FUN”? Thinking Twice About Stocking & Keeping Fishes by Professor Ellen Thaler
AQUARIUM PORTRAIT 74 HIGHS AND LOWS by René Vachovec
BACKGROUND: Turbinaria reniformis
Photo by W. Fiedler
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NEW PERSPECTIVES ON REEF LIGHTING by Anthony R. Calfo
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SPOTLIGHT:
The Bubble Tip Anemone by Robert M. Fenner
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REEFKEEPING 101: What is Ozone? by Daniel Knop
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ADVANCED AQUATICS:
Designing a Dream System by J. Charles Delbeek
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REEF LIFE by Denise Nielsen Tackett
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LETTER notes from DANIEL KNOP
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riggerfishes are generally regarded as aggressive ruffilook at our husbandry practices. In the International ans—and there is no denying that for the majority of Year of the Reef, which has just ended, many organizaspecies, this reputation is justified. It is often recomtions arranged conferences and exhibitions in order to mended that they be kept singly in species tanks. The bring the man on the street closer to the coral-reef enaquarium maintenance of many species is generally vironment and introduce him to the fascinating organnot advised at all, as the aquarist simply cannot proisms that live there. We aquarists already enjoy a greatervide for the requirements of these fishes when they than-average insight into this environment, but we need get large and aggressive. But some species are able to to be mindful that it is a great privilege to keep creatures live together in relative harmony in the reef aquarof the coral reef. With each fish or coral we bring home ium, as long as certain points regarding tankmates and comes the responsibility to keep it in optimal conditions feeding are borne in mind. and do nothing to shorten its expected life span. Many triggerfishes grow very large and need to con There is much to suggest that the spotlight will be sume enormous amounts of food during their growing on the reefs even more in future than hitherto. This is phase, which makes them greedy not only because of their vulnerabilaquarium occupants and their reity to environmental degradation, quirements abundantly clear. If their but above all by virtue of their ushunger becomes stronger than their age in human society, for example behavioral instincts at any stage, in modern medicine, where marine then bad times do indeed lie ahead organisms are being increasingly recfor cleaner shrimps, which are reognized as sources of highly effective garded as off-limits for most reef chemical compounds. And there is fishes. A well-fed trigger will seldom, still so much to be discovered beneath if ever, eat a cleaner shrimp. Oththe waves—for example, the undererwise, these adept crustacean helpwater mountains, or “seamounts,” mates would long ago have become estimated to number 100,000, the extinct in the wild. If a triggerfish in majority of which apparently possess the aquarium picks off your favorite a coral reef–like community. To date, cleaner shrimp, take it as a sure sign only a fifth of one percent of these that the fish was driven by hunger have been investigated and studied, and not by its natural instinct— and almost nothing is known about a reminder of the need for providthe potential importance of these Daniel Knop, founding editor of KORALLE ing appropriate food for each species ecosystems vis-a-vis the coral reefs we keep. that are already known. Seamounts may play a part in Apropos of this, it is never a bad thing to reconsider larval drift, and may even represent indispensable way the fundamentals of our aquarium maintenance of coral stations in the distribution of larvae from coral reefs! fishes; nothing in this world is so good that it cannot Finally, it is with great pleasure that I welcome editor be improved. Behaviorist Ellen Thaler has a number of and publisher James Lawrence, associate publisher Anthings to say on this theme, and not for the first time: thony Calfo, and the new creative and publishing team, her article relates to a piece she wrote years ago for the who have produced this, their first issue of CORAL. We, journal DATZ . Its publication at that time, under the and the many writers and photographers who have been title “Fish Polemic,” struck a chord in many readers, and friends of both KORALLE and CORAL for years, are conthere is good reason to believe that her latest article on fident that the magazine is in good hands and has a clear the subject will do the same. mission to bring you new ideas, new perspectives, and Moreover, as we become more aware of human and exciting content that will help you get more out of your climatic impacts on coral reefs and take a greater interest marine aquarium and reef-keeping experiences. in protecting the species-rich marine ecosystems of our planet, it is important for all of us involved in the marine Happy reading! aquarium hobby to take a critical—and introspective—
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w e l c o m e t o t h e n e w CORAL
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ne of our treasures from decades of keeping marine aquariums is a tattered, saltstained, dog-eared, autographed copy of a little volume called The Marine Aquarium Handbook. For the whole first generation of reef aquarists, this was our touchstone and bible as we daringly set up our first saltwater systems. Dated 1982, this book appeared at a time when many still believed that marine fish were impossible to keep, when live rock and skimmers and metal halides were unknown—a time when the idea of sustaining live corals in captivity was scoffed at by preeminent biologists. In the past weeks, as we undertook the humbling responsibility of publishing CORAL, the world’s original magazine for marine aquarists, we turned once again to our trustworthy mentor and author of that classic text, Martin A. Moe, Jr. Currently immersed in breeding experiments with the sea urchin Diadema antillarum in his home laboratory in the Florida Keys, Martin readily agreed to join us. Here is the response he sent. It is vintage Moe, literate and thoughtful and perfectly summing up what it is that brings all of us together to support a magazine like CORAL. “There is a fascinating and even primal attraction to marine aquariums that lies deep within the psyche of most people. It seems to go beyond the technical, artistic, and scientific satisfaction of creating and/or exploring a miniature replica of a marine aquatic ecosystem within our own terrestrial world. “Perhaps this is keyed to the instinctive drive to explore and understand our environment that has allowed us to survive and thrive ever since humanity first emerged. We are, and have been for a very long time, greatly captivated and enthralled by life from the sea in all its primitive complexity abiding behind glass within our own environment. “Keeping marine life in captive containers is not a new endeavor. It actually dates back to 1846, perhaps even earlier, but this was when Mrs. Thynne of London kept various invertebrates sent to her from the coast in a stone jar for many months of study and entertainment. “Water changes occurred every three months and the organisms were kept alive by manual aeration. As Mrs. Thynne reported, ‘I thought of having it aerated by pouring it backwards and forwards before an open window,
Martin Moe collecting plankton in the Florida Keys
for half to three quarters of an hour between each time of using it. This was doubtless a fatiguing operation; but I had a little handmaiden, who, besides being rather anxious to oblige me, thought it rather an amusement.’ “Yes, we have come a long way, and most of that journey has taken place in the last 45 years. “For me, the journey began in the early 1960s. I was a graduate student at the University of South Florida and a fishery biologist at the Marine Research Laboratory in St. Petersburg. I did a project for an animal behavior course on the breeding behavior of two species of blennies. The aquarium system consisted of twelve 10- and 20-gallon slate bottomed, stainless steel–framed tanks with bubbleup corner filters, a “state of the art” facility. This old study is now available on the Internet. How’s that for a blending of the old and the new? “But of course it is the new that we seek out most diligently. And there is so much now that is new. It is always important, and greatly fascinating, to keep up with what is happening in the marine environments of our world and in our endeavors with captive marine life. I am pleased to learn that CORAL, a premier magazine in this hobby and chronicler of all that is new and exciting, is gaining a new life. “I am most happy that CORAL has fallen into your purview, and I look forward to many more issues of spectacular photos and interesting and accurate information on marine aquarium systems and captive and wild marine life. All the best to the new CORAL.”
To all faithful readers and supportive sponsors who have been so encouraging during this relaunch of CORAL, we thank you and hope you find inspiration within these covers. To Daniel Knop and Matthias Schmidt, the enlightened founders of the parent magazine KORALLE, we can only say we hope to be good stewards of this journal. And finally, we extend our sincere gratitude to all the marine scientists, authors, underwater photographers, and lovers of the sea and of coral reefs who have rallied to join us in bringing you this magazine. —James Lawrence Charlotte, Vermont
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f ro m o ur rea der s
KUDOS
Ever since Daniel Knop started the original German edition of KORALLE, I have looked forward to receiving each issue, because it always covers subjects that fascinate me: aquariums, fishes, coral reefs, and the natural world. Daniel and his publisher, Matthias Schmidt, consistently produce timely, very informative, and beautifully illustrated magazines, and with the appearance a few years ago of an edition published by Leng Sy in the United States, English-speaking hobbyists were at last treated to this wonderful resource. I’m so glad to know that you have taken on the publication of CORAL so that it will continue to inspire involved aquarists and pet dealers. I’ve always admired the many books your Microcosm crew has published and produced, and know that your involvement in CORAL Magazine will assure a standard of information and print quality that is second to none. This is a magazine that is to be saved and absorbed over time, not merely glanced at and tossed. Julian Sprung, President Two Little Fishies, Inc. Miami Gardens, Florida CHANGING TIMES
Congratulations on the relaunch of CORAL. I look forward to the continuation of the magazine’s famously high standards. I also applaud your intention to support good local marine aquarium shops. In this faltering economy, far too many of them are being forced to close their doors. As a former shop owner myself, I know all too well the challenges they face, even during the best of times. Many independent retailers see big discount stores and e-commerce as the major threats to their survival. Some hobbyists will purchase deeply discounted livestock, irrespective of the risks involved, with no thought to the impact this may have on the hobby itself. I have nothing against people wanting to save a few dollars, but if we hobbyists don’t support our local shops, we will soon have none. Where I live, seven shops once thrived within half an hour’s drive of downtown. Now there are only three, and one of them may soon close its doors. I hear things are no better in many other parts of the country. By choosing not to support the dealer down the street, hobbyists not only take their dollars out of the lo-
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cal economy, but also threaten the survival of the hobby. The local, independent retailer has always been the place where newcomers get their start. How many people do you know whose interest in aquariums was inspired by a website versus the number who saw a beautiful reef tank on display in a shop? Our hobby must return to its local roots, or the entire industry can collapse. When the number of aquarium hobbyists falls below a critical point, even the biggest online stores will be forced to close. It’s not all bleak, as I firmly believe it is possible to have both a growing hobby and successful, independent local shops. Years back, the arrival in town of a national big-box retailer quickly killed off every mom-and-pop hardware store in my area. Folks whose business had been started by their grandparents had to retire or seek other employment. Now, however, several small hardware shops have returned. Why? At a big box, you are just one of the crowd, often with little or no trustworthy staff available to offer advice and answer questions. At a small shop, the staff will take time to understand your project. They have the experience to help you choose the right tools and materials. Nothing beats a good retailer who takes a personal interest in the success of every customer. This was the key to my store’s success, and it remains the key to success for aquarium shops and their customers. If aquarists will once again realize this, our hobby has a chance. John Tullock Knoxville, Tennessee WET�DRY MAGAZINE
As a passionate marine aquarium hobbyist, SCUBA diver, and amateur underwater photographer, I await the debut of the new CORAL Magazine with keen anticipation. With its evolution from the European KORALLE, and in the extraordinarily capable hands of its new publishers, I look forward to a wonderful combination of substance and style that is both intellectually stimulating and a near-perfect conversation starter for my coffee table. The trick will be to avoid picking it up with wet hands after working in my aquarium. Michelle Lemech Los Angeles, California
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NEWS f i nd in gs an d h appe ni n gs o f no t e
The mystery of the Facetotecta larvae For more than a century, the marine larvae bearing the name Facetotecta managed to conceal the identity of their adult form from science. The larvae were known, but what creatures had produced them, and what they would grow into, remained a mystery. They had been found in all the seas of the world from the Arctic to the tropics, but they could not be matched to any adult creature, and not even the most basic information was known about the ecology of the species. Finally, Danish and Japanese researchers treated the larvae with a hormone secreted by crustaceans that stimulates metamorphosis, and watched to see what would develop from them. The result was a big surprise: in the course of the maturing process the shrimp-like Facetotecta larvae shed their external skeletons, and what appeared was a soft, slug-like marine creature with atrophied eyes and musculature. The scientists felt that this creature was reminiscent of species with a parasitic existence, and thus they now assume that Facetotecta is a parasitic organism. ON THE INTERNET
Glenner H., J. T. Høeg, M. J. Grygier, and Y. Fujita. 2008. Induced metamorphosis in crustacean y-larvae: Towards a solution to a 100-year-old riddle. BMC Biology 6:21.
Medications from the sea Numerous sponges, as well as corals, bryozoans, and other marine creatures, are prevented by their sedentary lifestyle from fleeing from predators and hence have to protect themselves in other ways. They employ powerful sting-cell poisons and chemical repellents to serve this purpose. The bryozoan species Bugula neritina deThe secondary metabolites from marine sponges possess an enormous potential for medical research and treatment.
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The palytoxin from this encrusting anemone (Protopalythoa grandis) is produced by bacteria.
fends itself with an agent that has been given the name bryostatin. This substance not only is effective in frightening away enemies, but also can limit the growth of cancer cells in humans. Bryostatins are said to be especially effective against leukemia, and for this reason they are currently being tested in clinical studies. To date, the main barrier to the use of this substance has been that bryozoans contain extremely small amounts of it, so that large numbers of them would have to be harvested from the wild, which is unacceptable. One alternative might be the artificial breeding and culture of Bugula neritina, which is not currently possible. Over the past two decades, many thousands of metabolites have been isolated from sponges, algae, and higher life forms—for example, the didemnins (from a tunicate, or sea squirt, of the genus Didemnum) and eleutherobin (from a soft coral of the genus Eleutherobia). Marine life forms contain agents effective against diseases such as cancer, AIDS, herpes simplex, and numerous others. Marine life forms are generally among the most important and productive sources of new natural chemicals for use in human medicine, but no reliable method for extracting them has been discovered. But scientists have now discovered that in many cases these substances are not manufactured by the animals themselves, but by symbiotic bacteria that live within them. The above-mentioned bryozoan species Bugula neritina derives its bryostatin from bacteria. Margo Hay-
P O N K . D : S O T O H P
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good of the Scripps Institution of Oceanography discovered the factor that is responsible for the production of bryostatin. Antibiotic treatment of the bryozoans, which eliminated all bacteria but did not harm the bryozoans themselves, actually led to a decrease in the bryostatin content. Scientists regard this as evidence for the bacterial origin of the substance. This should come as no surprise, as it has been known for a long time that some substances with a highly toxic effect on humans are produced by bacteria: examples include tetrododoxin, which comes from many of the puffer-like fishes, the Tetraodontiformes, and palytoxin, which is found in the zoanthid genera Palythoa and Protopalythoa. This may mean that bryostatin, and perhaps numerous other secondary metabolites from other sea-dwellers, could be harvested outside the sea. In addition, a bacterium is much easier to influence by genetic manipulation than a highly evolved organism such as a sponge, a bryozoan, or a coral. All this also suggests that in the years to come, the use of marine secondary metabolites in human medicine may develop by leaps and bounds. —Daniel Knop
Undersea mountain a paradise for brittle stars The peak of an undersea mountain south of New Zealand appears to be a paradise for brittle stars: recently researchers found dense aggregations there with more than 100 individuals per square meter. Undersea mountains are marine ecosystems that have some features in common with coral reefs, and there is much to be said for regarding them as a further epochal discovery in marine biology—much like the “black smokers” in the marine abyss and the Lophelia pertusa
Above: Sorting samples on board the research ship Tangaroa Right: Macquarie Ridge on the map
reefs off Norway. Whenever biologists study such an undersea mountain and its marine inhabitants, they come across species that were previously unknown to science. As a rule, a site like this houses a relatively species-rich community that has colonized the elevated structure of the mountain via larval drift and created an ecosystem consisting mainly of sponges, corals, and other associated life forms. According to scientists’ estimates, there are around 100,000 such undersea mountains worldwide, and only 200 of them have been studied, so there is enormous potential for the discovery of previously unknown species of animals—and sometimes entire ecosystems. One example of this is the investigation of the Macquarie Ridge Seamount on an underwater formation known as Macquarie Ridge, which consists of a series of folds in the seabed extending for about 1,600 km to the south of New Zealand. Within the framework of the international global project “Census of Marine Life,” scientists from numerous disciplines are endeavoring to catalog all Close-up of the various inhabitants of the undersea mountain: brittle stars, sea anemones, sponges, soft corals, and worms.
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the organisms of the marine world. KORALLE has already reported on this several times. An interdisciplinary research team from New Zealand and Australia examined Macquarie Ridge and its ecosystems during a four-week expedition, using the latest video-recording equipment. The investigation was part of a planned study of undersea mountains termed the “Global Census of Marine Life on Seamounts (CenSeam)” under the auspices of New Zealand’s National Institute of Water & Atmospheric Research (NIWA). It was financed mainly by the New Zealand Foundation for Research, Science and Technology Tech nology.. What the scientists found at Macquarie Ridge was a unique ecosystem that consisted mainly of brittle stars. There were many millions of arms reaching up from the substrate into the open water to capture passing plankton; and over the flat top of the undersea mountain, an area of around 100 square kilometers, there was nothing to be seen but brittle stars—which in this environment need to do nothing more than extend their arms to obtain food. The foot of the mountain lies at a depth of 850 meters, while the peak extends to within 90 meters of the surface. Macquarie Ridge is one of the very few places that is affected by the endless circling of the Antarctic circumpolar current at the most southerly latitudes, mingling the waters of the Atlantic, Indian, and Pacific Oceans. At approximately 110 cm/sec, the current is very strong, apparently protecting brittle stars from predators and at the same time bringing them a constant and plentiful supply of food. According to Dr. Mike Williams of NIWA, this circumpolar current is around 110–150 times as strong as the currents of all the rivers of the world added together. Essentially, New Zealand is situated very close to the freeway, so to speak. The crew of the research ship Tangaroa christened the mountain top “Brittle Star City,” photographed and filmed the unique community, and took countless sam-
ples that may require years to study and catalog. Though experts do not entirely agree regarding the identity of the species, after initial studies taxonomist Tim O’Hara believes that the smaller, black-brown individuals, which live on the top of the mountain and extend a forest of arms into the open water, are Ophiacantha otagoensis or O. fidelis, and that the larger, orange-red ones, which hold their arms out into the current lower down on the flanks of the mountain, are O. rosea. Ecologist Dr. Ashley Rowden of NIWA regards the huge aggregation of brittle stars on the Macquarie Ridge seamount as sensational, not only because such a large number of similar organisms exists in one place but also because of the unique composition of the population, which will have a mas-
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sive effect on scientists’ understanding of undersea mountains as ecosystems. —Daniel Knop ON THE INTERNET
CenSeam: Global Census of Marine Life on Seamounts— part of the global Census of Marine Life (CoML) CoML is an expanding global network of researchers from more than 80 nations working to catalog, within the space of a decade, all species of marine life, past and present, along with their distribution and frequency. http://censeam.niwa.co.nz/ CenSeam news release: http://censeam.niwa.co.nz/__ data/assets/pdf_�le/0009/ data/assets/ pdf_�le/0009/71658/C 71658/CenSeam_MacRidge_ enSeam_MacRidge_ Press_Release.pdf
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The most ominous T phenomenon faced by p ccoral reefs globally is bleaching on a massive bl scale. In a joint effort by sc some 50 international so scientists at NOAA, the sci Australian Great Barrier Au Reef Park Authority, and Ree the International Union for the Conservation of Nature, a new 178-page book on the causes and consequences of bleaching has been published and is now available for free download at the URL below. http://coris.noaa.gov/activities/reef_ managers_guide/
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Anyone seeing a “black smoker” in the marine abyss for the first time will feel transported into an alien world. In its scientific program “Projekt Zukunft (Project Future),” DW TV showed viewers viewers unusual glimpses glimpses into this realm of darkness. The German television company, together with the MARUM Research Center in Bremen, Germany, produced a five-part series called “Expedition zum Meeresgrund (Expedition to the Ocean Floor).” Scientists at the MARUM Research Center took the viewer along on diving trips to the methane gas fields in the Indian Ocean, the asphalt volcanoes in the Gulf of Mexico, and the cold-water coral reefs of the Mediterranean. Viewers accompanied scientists on a drillship in the Arctic Ocean, heading for the North Pole. And in the middle of the Atlantic, where new seabed is constantly being created, the viewer could see for himself just what a “black smoker” is like. The director of MARUM, Professor Gerold Wefer, said the aim of the
N E M E R B T Ä T I S R E V I N U , M U R A M
Black smokers are hydrothermal vents, found in �elds hundreds of meters wide, formed when superheated water from below the earth’s crust comes through the ocean �oor. Dissolved minerals, most notably sul�des, precipitate in contact with cold ocean water, forming a chimney-like structure around each vent.
scientific films was immense and that letters from all over the world confirmed this. Viewers were especially keen on seeing information about German research. The series “Expedition to the Ocean Floor” was broadcast weekly beginning June 8, 2008, in both German and English, as well as German with Arabic subtitles. The series is also available as “video on demand” or can be downloaded. —Source: IDW
media partnership with DW-TV was to engage the international public with the subject of deep-sea research and the work of the research center. DW-TV Director Christoph Lanz stated that viewers’ interest in exciting
ON THE INTERNET
http://www.dw-world.de/projektzukunft http://www.dw-world.de/tomorrowtoday http://www.marum.de
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t e x t a n d p h o t o s b y INKEN KRAUSE
Periclimenes brevicarpalis in the aquarium, on a Haddon’s carpet anemone (Stichodactyla haddoni ). Note the two striking ocelli (eyespots) on the tail �n (on the left) in contrast to the inconspicuous head with its barely discernible real eyes.
The Partner Shrimp Periclimenes brevicarpalis
Periclimenes brevicarpalis is a small, delicate shrimp that many aquarists fail to notice at first glance because it is largely transparent and usually spends its time hidden among the tentacles of sea anemones. In the wild, this species, which attains a maximum length of about 1.5 inches (4 cm), lives alone or in harems on the sea anemone Cryptodendrum adhaesivum . Although P. brevicarpalis exhibits no distinct sexual dimorphism, males are larger than females and have a tendency to develop heavier spotting. Because males are
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aggressive among themselves, a harem, with one male and several females, is recommended for aquarium maintenance. However, it is also possible to keep several males in a large aquarium containing several host anemones. In aquaria without any host anemones, a var iety of large-polyped hard corals, as well as encrusting and disc anemones, are acceptable substitutes. When it comes to diet, P. brevicarpalis is not very fussy; although it will happily take the usual frozen and dry foods, it may still prey on its own host anemone. Thus, though fascinating, this combination of creatures is not pure symbiosis. When the species is housed with very large sea anemones, such as the natural host Cryptodendrum adhaesivum (unfortunately very rarely available in the aquarium trade) or other large sea anemones (for example, Stichodactyla spp.), it is rare that there is any noticeable damage to the host. Either these large sea anemones are able to compensate for damage by the little shrimp, or they are capable of preventing such damage
using protective mechanisms that are lacking in an unnatural host such as a large-polyped stone coral. Periclimenes brevicarpalis thus cannot be recommended for aquarium maintenance entirely without reservations. It may damage sessile invertebrates to a limited degree. It does best in a peaceful aquarium with no large fishes that might regard this tiny crustacean as food. The very large sea anemone necessary for the correct maintenance of P. brevicarpalis is totally unsuitable for the average small aquarium. Interestingly, this little shrimp is decorated with ocelli, not only because of its relationship with the host, but also because they provide an excellent method of deceiving potential predators. The two dummy eyes on the tail fin (see photo) disguise the real head and hence the direction of flight as well. The tail fin looks like a head to the would-be predator, while the real head and eyes are inconspicuously colored. When the shrimp flees, it will leave the predator grabbing at nothing. REFERENCES
Thaler, E. 2003. Auge oder Scheinauge—das ist hier die Frage. KORALLE 23:34–37.
The Longfin Anthias Pseudanthias ventralis
The Longfin Anthias, Pseudanthias ventralis, is a rare fish that can’t fail to be noticed. With its gaudy pink and yellow coloration and its elongate finnage, this fish immediately catches the eye—on the rare occasions that it turns up in the aquarium trade at all. It is almost unbelievable that this bright coloration actually serves as camouflage. And yet, in the diffuse blue light of its natural habitat at a depth of up to 66 feet (120 m), the colors that are so striking under bright light are practically invisible. Like many other especially colorful fishes, P. ventralis occurs on the Great Barrier Reef off Australia. The species lives in large groups that populate vertical surfaces at great depths and snap up any planktonic organisms that drift past in the current. In the direction of Johnston Atoll and Hawaii, the species is replaced by the very similar P. hawaiiensis.
At first glance, P. ventralis appears to be well suited to aquarium maintenance. With a maximum body length of 3 inches (8 cm), the species remains very small in comparison to other anthias (for example, the very popular P. squamipinnis ), so that in aquaria of 250 gallons (approximately 1,000 liters) or more it can be kept in large groups in line with its natural way of life. Satisfying the dietary demands of these planktivores is—as with almost all anthias—difficult; in the final analysis, they should be given fine food such as Cyclop-eeze at frequent intervals in order to meet their high energy requirements. Ideally, food should be constantly available. Far more problematic, however, is meeting the special requirements of deep-reef dwellers in brightly-lit aquaria. The light conditions in modern reef aquaria are very different from those in the natural environment of this species. While there have been success stories about the maintenance of anthias from great depths, it cannot be denied that many of them do not live very long in the aquarium. And it cannot be ruled out that this is due to stress caused by too high a light intensity (and possibly too high a temperature). Anyone who is seriously interested in the maintenance of these splendidly colored fishes is advised to try muted lighting at the blue end of the spectrum. This will make the fishes feel most at home in the long term, even if in the blue twilight the bright coloration—which is, of course, the main attraction of this species—loses much of its effect. REFERENCES
Kuiter, R. and H. Debelius. 2006. Atlas der Meeres�sche. KosmosVerlag, Stuttgart, Germany. On the Internet (8-16-08), FishBase: http://�shbase.de/Summary/speciesSummary
Pseudanthias ventralis , photographed
in the De Jong M arinelife display aquarium at the Interzoo 2008.
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The Clarion Angelfish Holacanthus clarionensis
The Clarion Angelfish, Holacanthus clarionensis, is distinguished from its equally attractive relatives in the genus Holacanthus primarily by its extremely high price. An investment of at least $3,000 may be required to call this exclusive angelfish your own. And even those who are prepared to invest such a sum in a single fish will discover that they are extremely difficult to find in the aquarium trade. The Clarion Angelfish is not especially rare in the wild, however, even though its distribution region in the central eastern Pacific off Mexico (above all at the Revillagigedo Islands) is very small. What probably makes it rare is the high cost of collecting and transporting it from its isolated range—possibly also a clever export policy. H. clarionensis is particularly beautiful in its juvenile coloration, when it exhibits a brass to orange base coloration with a pattern of brilliant blue stripes. This pattern disappears in adult individuals, and sometimes the orange also becomes a bit “washed out” and tends Juvenile Holacanthus clarionensis , photographed in the De Jong Marinelife display aquarium at the I nterzoo 2008. The blue stripe pattern on the body will disappear with age.
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more to brown. But the fabulously beautiful blue fin edgings and the characteristic blue lips (otherwise known only in the Flagfin Angelfish, Apolemichthys trimaculatus) are retained. Pragmatists will maintain that the species is not appreciably more attractive than its much more reasonably priced relatives—for example, the Caribbean Holacanthus ciliaris—but beauty does, after all, lie in the eye of the beholder. On the credit side, H. clarionensis is exceptionally well suited, relative to other large angelfishes, to aquarium maintenance. At around 9.8 inches (25 cm) it is smaller than other species of the genus; nonetheless, it is relatively robust, and like all large angelfishes should be provided with adequate swimming space. It must be borne in mind that corals and other invertebrates in the aquarium will constitute part of its diet, but anyone who is prepared to pay for such an expensive fish will undoubtedly not be put off by this dietary preference. REFERENCES
Kuiter, R. and H. Debelius. 2006. Atlas der Meeres�sche. KosmosVerlag, Stuttgart, Germany. On the Internet (6-08-08), FishBase: http://�shbase.de/Summary/speciesSummary.php? ID=11172&genusname=Holacanthus&speciesname =clarionensis
D a n i e l K n o p t a l k s w i t h DENISE an d LARRY TACKETT
Denise and Larry Tackett are dive professionals and nature lovers who have devoted their lives to the observation and documentation of marine organisms on tropical coral reefs. Around 25 years ago, the two of them left behind their chemical industry and banking careers so they could do what they really enjoyed: experiencing and photographing nature. They began with a part-time job collecting marine sponges for a university doing cancer research, which left plenty of time for wildlife photography, and later started working full-time as a wildlife photographer-and-author team.
Above, Denise Nielsen Tackett photographing a giant stingray, Daysyatis sp. Right, the Tacketts at one of their favorite bases, Kungkungan Bay in Lembeh Strait, Sulawesi.
For two and a half decades, the Tacketts have been living in various remote parts of Indonesia, Malaysia, Papua New Guinea, the Maldives, and Palau, as well as on Mauritius and in other countries, in order to dive—as part of their work, but also for pleasure. They have built an immense photo archive, and their luminous photos and well-researched articles have been published worldwide in books and magazines. National Geographic has reported on their work on seahorses and in the Lembeh Straits. A few years ago Denise was honored by having the seahorse s pecies Hippocampus denise named after her; this is the smallest seahorse known, attaining no more than a half inch (14 mm) in length. Denise and Larry have also jointly published an acclaimed book, Reef Life—Natural History and Behaviors of Marine Fishes and Invertebrates. CORAL: Denise
and Larry, let me start with a rhetorical question. Have you ever regretted your decision, back in the 1980s, to leave your professional lives behind and begin your never-ending coral-reef adventure? Denise: No.
I’ve never once regretted leaving my secure, established life behind. In fact, I can’t imagine living any ot her way now. Before we left, I worried that we’d be sorry one day, but it’s been over 20 years and that day still hasn’t come. I’ve learned so much from living in other cultures and from observing and photographing nature that I often wonder how I survived without it in my former life.
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Opposite page top: Purple Anthias (Pseudanthias tuka) swim over a formation of Yellow Scroll Coral (Turbinaria reniformis) in the Bismarck Sea. Bottom: Female Longnose Seahorse (Hippocampus trimaculatus) on driftwood
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Clockwise from top left: Small dragonet (Synchiropus sp.). Close-up detail of colonial sea squirts ( Botryllus sp.). Small Rosewater’s Cowrie (Crenavolva rosewateri ) feeds on its host, a melathaeid gorgonian. Large gorgonian (typical habitat for Hippocampus denise) with feather stars (Crinoidea) on reef.
Our years of uncertain adventures helped me to view life from a different perspective and to reorder my priorities. I also had the luxury of exploring sides of myself I never knew existed. Larry: For me, seeing the world and creating photo-
graphs was my dream from an early age. From the time I finished college and began an engineering career, I had something of a parallel life. I was always tr ying to learn more about photography to the extent that I started to teach photo courses at a variety of community venues. I actually began to dive so that I could t ake images underwater. I used all my available vacation time to take dive trips and even became a dive instructor. The first class I taught included Denise as the divemaster and a man that would later offer us the opportunity to begin our life with the sea. Over 6,000 dives and 25 years later, I have no regrets. I cannot imagine my life having developed any other way. Is there a group of animals that you �nd particularly fascinating? What do you look out for when you �rst dive on a coral reef? CORAL:
underwater and on land. I think I’m more interested in the variety of and commonalities between the behaviors of different groups in nature. There are many parallels between the terrestrial and underwater worlds. Camouflage is one example: a moth that disappears on the bark of a tree, a pygmy seahorse disappears on a gorgonian, and an octopus often blends into the reef. Each species is vastly different yet they use similar tactics for survival— that’s what fascinates me. Warning colors are another example. Think of colorful nudibranchs advertising their toxins or unpleasant taste to would-be predators and compare that to beautiful butterflies whose coloration also warns predators away. It’s as if there’s a thread of oneness that runs through the fabric of all life, connecting it in ways we don’t notice unless we really think about it. That fascinates me. Larry: At first, I found sharks and larger reef life interest-
ing. After a few hundred dives I, and of course Denise, began to look at the reef in a different way—not just for individual animals to see and photograph, but also for observable behavior that we could record on film. As this interest developed, I began to look at smaller and smaller animals, seeing what the majority of divers overlook as they swim past to pursue larger marine subjects. Our arrival in Indonesia marked a turning point in our undersea experiences. For the first time, we were finding animals we’d never seen before. Rare and unique animals were all around us, seemingly waiting to be recorded on film. So I guess I would say seeing and recording behavior is of most interest to me, not just a particular species of animal. Would you say there are any places in the world where you have most enjoyed your diving? Or places that you would like to explore in the future? CORAL:
Denise: I certainly have a special interest in pygmy sea-
horses but I’m interested in many different groups—
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Denise: I think every place I’ve dived has something unique
that makes it special, but Indonesia and Papua New Guinea are my diving favorites because of the extraordinary diversity and the abundance of marine life inhabiting that area. The area surrounding the island of New Guinea is particularly remarkable because so little of it has been fully explored. I could spend a few lifetimes there. Also high on my list of favorites are the Maldives and Kangaroo Island in South Australia.
A pair of superbly camou�aged pygmy seahorses, Hippocampus denise, cling to their host gorgonian. The species is named in honor of Denise, who �rst photographed and studied them in Sulawesi.
served these fascinating little �shes over a long period, and after a certain time you became convinced that they must be a new species. Pease tell us the story behind this. Denise: I had looked for pygmy seahorses for many years
Larry: Without a doubt, Indonesia is my favorite place to
dive and explore. I find the range in habitats and marine life in general to be the most diverse of any place I have been. When we arrived there in 1995, the diving world was just beginning to discover the incredible diving opportunities there. Lembeh Strait was all but unknown; now it is a well-known and heavily visited area, with many resorts. Perhaps the most appealing aspect of Indonesia is that there is still a frontier where few have been and many locations have yet to be visited. I always like to say that even after a couple of thousand dives in Indonesia, I can still go in the water and have an excellent chance of seeing something, or some behavior, that I’ve never seen before. It doesn’t get any better than that! CORAL: Denise, for many years the pygmy seahorse Hip pocampus denise was regarded as simply an unusual color form of H. bargibanti . Together with Sara Lourie, you ob-
to no avail. I’d seen only one photo of them from the New Caledonia aquarium where they’d been found, by accident, on a gorgonian collected for the aquarium. In 1995-6, when we were working in Lembeh Strait, a dive guide in Bali found a pygmy seahorse on a gorgonian there. Once I found out what species of gorgonian they lived on, I started finding them in the Lembeh area. Then everyone had pygmy fever—divers were looking everywhere for more pygmy seahorses. One day, I was on a dive when a newly certified diver found an orange pygmy on a different gorgonian. I was one of the first to photograph it. It was hard to focus on it, because it was actively swimming up, down, and across the gorgonian —something H. bargibanti rarely does. When I was able to focus, I could see the different head and snout shape and the relatively smoother body. As I observed the tiny seahorse, I noticed some transparent shrimp on the gorgonian. Each time the seahorse approached one of the
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shrimps, it would reach out and nip the seahorse on the head. I was convinced it was not H. bargibanti . I searched other gorgonians and found more pygmies that resembled the new one, so I knew it wasn’t an anomaly. I contacted the leading seahorse authority, Amanda Vincent, for more information. She said there was very little known about pygmy seahorses and she had no idea if it was a new species or just another form of H. bargibanti . I showed my photos to Gerry Allen and Jack Randall(Drs. Gerald R. Allen and John E. Randall), the world’s leading fish identification experts—they didn’t know either. So I began observing both types of pygmies and keeping detailed records of their behavior, as well as a photographic record. I conferred with one of Dr. Vincent’s students, Sara Lourie, who eventually joined me in Indonesia and agreed to look into the possibility that the orange pygmy seahorse might be a different species. The first time I dived with Sara, I took her to one of the gorgonians with H. bargibanti that I’d been observing. We planned to measure the seahorses, something that proved to be more difficult than we’d imagined. Sara was able to coax one off its branch. She held it very gently between her fingers as I prepared to photograph it alongside a ruler. The tiny seahorse started to flick its tail and each time it did, it forced tiny, fully formed baby seahorses into the water column. We watched in awe as the pygmy gave birth to 34 tiny seahorses! It was one of
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Commensal Emperor Shrimp ( Periclimenes imperator ) near the gills of its host, a Spanish Dancer nudibranch ( Hexabranchus sanguineus).
the most amazing moments of my life. After that, we continued to correspond and compare notes. I continued my observations and we were able to get government approval for sample specimens of H. bargibanti and the new orange pygmy to be used for scientific purposes. Sara and Jack Randall did the scientific work that proved what I suspected all along—that the orange pygmy was indeed a different species of pygmy seahorse. When Sara told me they named it Hippocam pus denise, I was totally surprised and absolutely delighted—it was another one of those amazing moments. CORAL: What
was your closest call with a potentially dangerous marine �sh or animal? Denise:
Years ago, on my first dive in Papua New Guinea, I encountered my very first sea snake. I’d been searching for one so I could photograph it. Unsuccessful, I ascended to the surface and signaled for the boat before realizing an olive green sea snake had wrapped itself around my arm. At that moment of mutual recognition, we both sprang into action—the snake slipped off my arm and descended as I followed in hopes of getting
a photo. My photo was a fuzzy tail shot but I learned an important lesson that day: even the most venomous marine animals are as scared of you as you are of them. That realization guides me even today because I try to respect and forge a bond with animals before attempting to photograph them—something I believe leads to better images. Larry: My closest call was on a dive in Indonesia with
a sandy bottom. I’d been kneeling in the sand while I photographed some invertebrates on an isolated coral head. I inched closer to my subject, checking the sand
along the way so as not to crush some small, unsuspecting critter. Just as my right knee touched down, I felt a bump and saw a flurry of sand that finally settled a few feet away. Much too my surprise, it was a venomous Spiny Devilfish that had been buried just under the sand! Had it not fled, I would have knelt on it, leaving the fish only one option: to sting me with its venomous spines. Now I never kneel or touch anything underwater without having a second look. CORAL: Denise
and Larry, thank you very much for
this interview!
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TR T RIGGERFISHES
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almost like something out of a science fiction film—the rhomboidal body of a triggerfish glides calmly along, propelled only by the undulating movement of the edges of the fins that surround the rear third of its body. No beats of the tail, no paddling pectoral fins. It looks like a swimming head, as the jaws are so powerful that the
Niger Trigger�sh, Odonus niger
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Black Trigg Trigger�sh, er�sh, Melichthys niger
Pinktail Trigg Trigger�sh, er�sh, Melichthys Melichthys vidua
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head occupies the entire anterior third of the body. The between the substrate and the underside of the urchin. mouth, by contrast, is almost tiny, and the gills are so Undulate Triggerfishes ( ) and Clown small that they often go unnoticed at first glance. Triggers ( ) are particularly skilled Triggerfishes get their name from a unique anatomiat this. Once the Diadem Sea Urchin—often considercal feature they all share: the very strong first ray of the ably larger than its attacker—has finally been freed from forward dorsal fin can be erected and locked in place by its resting place, the triggerfish uses its teeth to grasp its a small second spine to allow them to anchor in crevices victim by the outermost tips of the spines and drags it and thwart predators attempting to pull them out; the away to a suitable working place, usually a depression in second ray, in triggerlike fashion, can be depressed from the sand. To start with, the tips of the spines are succesthe locked position to release the first spine. sively shortened (and eaten), so that t he mobility of the Triggerfishes belong to the order Tetraodontiformes (puffer-like fishes), and the resemblance is easy to see; in spite of the much-compressed body, a number of similarities to pufferfishes are clearly visible. Moreover, the differences from the members of the order Perciformes (perch-like fishes), to which the majority of coral fishes belong, are evident at first glance, even to the layman; triggerfishes are, quite simply, different. In addition, some triggerfish species exhibit a body pattern that looks rather like an abstract painting. There is a whole group of species decorated with works of art reminiscent of the Cubist movement. As a result, in many languages the name of the gifted Spanish painter Pablo Picasso appears in the popular terms for these species of the genus (Arabian, Blackbelly, Halfmoon, and Picasso Trigger). Numerous different factors may have been reBluelined Trigger�sh, Pseudobalistes fuscus: juveniles such as this are destined to grow large, with a maximum size of 21.7 inches (55 cm). sponsible for the evolution of the unusual color patterns of triggerfishes, but in the Picasso Triggers and a number of others, for example the Clown urchin is compromised. Then the triggerfish repeatedly Trigger ( ), on closer examination tries to turn the urchin over so that its mouth area faces it can be seen that the body coloration conforms to the upwards. Once it has bitten this region free of its coverrules of “counter shading.” This term refers to a type of ing of (already) short spines, it cracks the urchin open color pattern in which the upper surface is dark while with a number of carefully aimed bites to the mouth the underside is light. The reason for this is very simple opening; in the aquarium, these bites can be heard very and can be appreciated by anyone who has ever dived clearly! It is all over quickly, and all that remains is an or snorkeled in the sea: if one looks down through the empty shell, nibbled clean, covered with little more than open water by day, with no bottom or rock formations a stubble of spines. Now and then triggerfishes even pull in sight, the water appears dark. If, on the other hand, the Diadem Sea Urchin’s “jaws,” the so-called “Lanone looks up toward the surface, the water looks light tern of Aristotle,” from the shell fragments and nibble because of the daylight coming from above. It follows away every last remnant of tissue. When one finds such that a fish that has a dark dorsal surface will be easily sea-urchin remains on the reef, it is very obvious that overlooked by predators looking down from above into the predator was a triggerfish and not another urchinthe dark seawater. If it also has a light underside, it will eating fish. It is astonishing how even sea urchins hidlikewise be visible only with difficulty from below. This den in the sand are tracked down, blown free, and eaten. , the Queen Triggerfish of the Caribbean, “counter shading” is, of course, not an invention of the triggerfishes, but has evolved many times in the animal specializes in this type of hunting and particularly enkingdom through predation selection; another excellent joys cracking open . example is the Nautilus, for example . Although triggerfishes are not deliberately harvested Triggerfishes have also evolved to be aggressive. Even for human consumption, they do often turn up in fish relatively small juveniles are quite capable of tackling markets in tropical countries with long coastlines. Unlarge Diadem Sea Urchins: they start by “blowing” them like their relatives the pufferfishes, which secrete a toxin away from the substrate, usually positioning themselves called tetrodotoxin that is produced by bacteria, triggerat an angle in order to aim the jet of water accurately fishes are not fundamentally poisonous. Nevertheless,
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cases of poisoning from eating triggerfishes are common. The reason for this is a toxin that enters triggerfishes more by accident than by design, and by a devious route. Along with their food, triggerfishes sometimes eat the dinoflagellate , an organism that lives on algae and secretes a toxin known as ciguatoxin. This causes the poisoning syndrome known as ciguatera, which initially resembles a case of food poisoning (vomiting, diarrhea), but then affects the nervous system and causes neurological symptoms. Normally the concentration of this dinoflagellate in triggerfishes is slight, but occasionally there is a massive proliferation of the algae, which leads to increased con-
sumption of the dinoflagellate by algae-eaters such as sea urchins. These, in turn, fall prey to predators—including triggerfishes—in whose bodies the toxin accumulates. The triggerfishes themselves are not affected, as these sea-dwellers have experienced such close and continuous contact with numerous marine toxins during their evolutionary history that their systems have been able to develop immunity. But humans, who have rarely been exposed to these toxins (and only in the past few hundred years), sometimes react dramatically to this and other toxins produced by inhabitants of the sea. Ciguatoxin poisons between 10,000 and 50,000 people annually (Mebs 2000), sometimes up to 40 percent of the popu-
Bluechin Trigger�sh, Xanthichthys auromarginatus
lation on some islands in the South Pacific. One of the most striking characteristics of the triggerfishes is their assertiveness, in the aquarium as well as in their natural habitat. In the sea this sometimes goes unnoticed, even by divers and snorkelers, as Prof. Ellen Thaler describes in her article in this issue. But in t he aquarium this characteristic can be exacerbated by hunger: the enormous size that the majority of species attain as adults dictates a huge rate of growth, which, of course, raises their food requirement far above that of other fishes of the same size with an inappreciable growth rate. Not surprisingly, the result is that many triggerfish species are so vora-
cious in the aquarium that they will eat all the food offered, causing tankmates to go hungr y. For this reason, the choice of species in relation to tank size and other occupants is probably the most important criterion for the aquarium maintenance of triggerfishes, and only certain species are suitable for normal-sized tanks, as Professor Thaler relates. But despite all this, triggers are fishes of great character and, as such, highly interesting for divers, snorkelers, and naturalists. REFERENCES
Mebs, D. 2000. Gifttiere. Wissenschaftliche Verlagsgesellschaft, Stuttgart, Germany.
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Oh, those Triggers!
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T
riggerfishes are unusually appealing fish personalities.
They are also a real stumbling block for every novice in the aquarium hobby, as they are “must-have” fishes in the minds of most beginners. Almost immediately, and without further ado, triggerfishes are given names, even by those who are not nor mally inclined to anthropomorphize their fishes (which is, of course, all to the good). A triggerfish might be called Max because it looks just like Uncle Max—or behaves in the same “pushy” way. My own two Picasso Triggerfishes were christened Leopold and Leopoldine and had godparents, and there was a long and rather silly story attached to them (Thaler 1999). You either love triggerfishes or you hate them; there is no neutral ground. We sacrifice entire fish communities to them, along with heater-stats and hydrometers, pump components, cable connectors, and sometimes even the entire aquarium; and, if we are unlucky and the triggerfish has gnawed away the pipework, we even flood the house for them. Then, and only then, do we—usually—part with them. Triggerfishes are cunning rascals that can also be a little underhanded—or downright wicked! They are intelligent and always hungry, and it is this combination that causes the problems, as triggerfishes will do absolutely anything in order to obtain food. TRIGGERFISHES IN THE AQUARIUM?
R E L A H T . E : S O T O H P
And so we come to the million-dollar question: do triggerfishes belong in an aquarium? In a reef aquarium? Even fish-loving, long-term experts such as De Graaf, Klausewitz, or Chlupaty advise keeping a single triggerfish in a fish-only aquarium with large fishes that are able to look after themselves. Triggerfishes are subject to an outright ban in the higher echelons of reef aquarists; zoological gardens tend to keep them in the shark t anks, and that is not a bad thing because, in most cases, they get enough to eat now and then. And even such thugs as the Titan Trigger, the Clown Trigger, various Widow Triggers, and all the species that grow to half a meter or more can be accommodated thus with a clear conscience. Triggerfishes of all genera and species have one feature in common: they need to be fed well, and copiously, but sensibly; in other words, the old, old story. But triggerfishes let us know when they are hungry more emphatically than all other fish families, with the possible exception of the large groupers. And they really do seem Young Clown Trigger (Balistoides conspicillum) and Brown Tang ( Zebrasoma scopas) confronting one another.
Face-on, a Bluechin Trigger�sh, Xanthichthys auromarginatus, displays typical male coloration. Females lack the blue pigmentation. This species has small teeth and is reef-safe.
to be always hungr y! However, inquisitive aquarists like us should know that the food-hunting behaviors of triggerfishes vary. For instance, we find dangerously intelligent triggerfishes in the genera Balistapus, Balistoides, Pseudobalistes, Balistes, and Rhinecanthus. These are predominantly composed of species that seek out their prey near the bottom, and when they find it often behave rather badly. For example, the Green Triggerfish ( Balistoides viridis) and the Bluelined Trigger ( Pseudobalistes fuscus) will rip meter-long pieces of coral out of the substrate and turn them over if there is a crab inside, and it is not difficult to imagine how an aquarium-sized juvenile of such a species will behave when it is hungr y. They can be incredibly inventive, and the less well they are fed, the more inventive—or more accurately, reckless— they will become, until they actually get too weak for feats of strength. Unfortunately, triggerfishes are also masters of survival and can tolerate a lack of food for long periods. In no other fish family do we so often find deformed specimens as in triggers that have received too little food in too small an aquarium. Such specimens usually are mostly head, with tiny bodies and oversized
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At left is the Clown Trigger ( Balistoides conspicillum) in a typical threat display with open mouth and spines erect.
fins (and they always remind me of Gothic representations of children as dwarfed adults), and remain so for years until they die. But it doesn’t have to be that way. Quite the contrary: triggerfishes can positively enrich an aquarium through their presence, their multi-faceted behavior, and even their occasional acts of wickedness. And it is also possible to satiate their appetites without fouling the aquarium environment in the process. SPECIES SUITABLE FOR THE AQUARIUM
At present, I have two splendid Crosshatch Triggerfishes ( Xanthichthys mento), which I have to keep an eye on to some extent (for example, when they try to dig a breeding pit in a corner of the aquarium and are doing everything they can to cause an avalanche), but which are essentially very pleasant and friendly and do not harm bottom-dwelling blennies or dottybacks, or even cleaner shrimps. Every evening after the last feed, I give them the largely empty glass bowl I have been feeding from so that they can nibble it really clean down to the last tiny crumb: they wait expectantly for this treat and angle themselves rather neatly so they can watch me out of one eye as they scrape away. But when there really is no more left and I don’t take the food bowl, and my hand, out of the water in time, they often bite me—not hard, but as if to say, “That was nice, you can go now!” All in all, it is possible to maintain species of the genera Xanthichthys, Melichthys, Odonus, and, with some reservations, Sufflamen, fairly well in the reef aquarium, as this group also includes a lot of plankton hunters—provided you are willing to cater to their needs. That is to say, the food should not only be varied but should also include small particles such as Cy-
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clops as “occupational therapy.” You must also provide a varied aquarium landscape that offers “current channels” in various places, where the fishes can fully exert themselves. For example, the output from the pump can be aimed directly among a number of reef elements; the fishes will often remain for several minutes in the fiercest of the turbulence where they will use their full swimming power. Any other fish would simply be blasted away! Surprisingly, triggerfishes do not take any particular pleasure in variable current conditions, demonstrating that they are, in fact, rather conservative in their preferences: they always stubbornly seek out the same spots. Their least favorite places are those in which currents run directly along the front glass, where they are often prone to stereotypical panic swimming. This is perhaps a reaction to the water pressure from one side contacting their lateralline system. Naturally they like plenty of caves, tight crevices, passages, pillars, and coarse rubble, as well as fine sand. In such areas of shell and coral rubble they will exhibit their trigger-typical hunting behavior: first they drag the large pieces to one side and then they blow the sand away in order to get at some delicacy or other (but unfortunately, they don’t like bristleworms). Even predominantly planktivorous species like the Niger Trigger will behave in this way. Small crabs are apparently irresistible morsels; once they have captured one they will often dig in the same place for days on end! SEX�CHANGING
Triggerfishes are thought to be obligatory sex-changers. I have observed the utterly fascinating metamorphosis from female to male in three species. In the Bluechin Trigger ( Xanthichthys auromarginatus) and the Crosshatch Trigger ( X. mento) the transformation is particularly impressive: the initially rather unassuming grayblue-silvery Bluechin Trigger female, with her fascinating blue eye-rings and gossamer, almost transparent glassy fins, develops delicate golden fin edgings and only eventually the brilliant blue chin, or cheek, that gives the species its name. At this stage all the fins are edged with lemon yellow and the fish is some 6 inches (16 cm) long. The change in X. mento runs a similar course, but is somewhat less spectacular: the initially ochre-edged parts of the fins become brilliant yellow, the caudal fin turns to bright red, and the entire body takes on an intense greenish hue, the cheek stripes a vivid blue. In the
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Above, the common Picasso Trigger ( Rhinecanthus aculeatus) in its sleeping cave. Below, a Rectangular Trigger (Rhinecanthus rectangulus) inside and R. aculeatus in front
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This juvenile Bluelined Trigger�sh ( Pseudobalistes fuscus) is demonstrating the trigger�sh habit of blowing into the substrate in order to uncover prey. Below: Clown Trigger making a meal of its favorite food, a sea urchin that it has gotten into a vulnerable upside-down position.
deep black Melichthys ni ger, only the small “sail” of fin linking the three dorsal rays changes color to orange-red, while the white area at the base of the fin becomes wider. What does alter dramatically, however, is the behavior, above all when one of two female-colored fishes becomes aware of the impending change to male and begins to display. Trigge rfishes can be very “vocal” in their wooing; they chatter, grunt, and bark at every pitch when they court a female in the process of changing, and guide her to a spawning pit or to a corner of the aquarium where they will excavate one. And they don’t go about it at all daintily: it is rare that there are no scratches or fin damage, but these heal very quickly. This phase is rather uncomfortable for the aquarist, as the fishes, working frantically with teeth and thrashing fins and beating tails, try to excavate their pit as deep as possible and become angry when they reach the glass bottom—and perhaps also see themselves reflected there. I always try to cover the exposed bottom with large round pieces of coral that will be difficult for the fishes to grasp with their teeth, but I am always worried that the bottom may get cracked or collapsing fragments of reef will topple and break the glass (but, so far, so good!). If plastic is used instead, they rapidly tear it to pieces, and sooner or later they will shift flat, heavy stones out of the way or start digging in a different spot. And the
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spectacle of the fishes doggedly working so hard in this way is certainly impressive: clouds of “dust” envelop the aquarium, and all the fishes stand around inquisitively and watch with interest—albeit at a respectable distance, as otherwise they are chased away fairly aggressively. Really determined attacks are reserved for t he camera lens if it comes too close! But what rather spoils the pleasure of watching them is the fact that the female, who always spawns again several weeks later (in my tank the clump of spawn invariably disappears during the first night), will in turn begin to change sex. This is immediately apparent: there are regular noisy quarrels, the partners no longer swim together, and usually a change in fin color is already visible. And unless the pair are now separated very rapidly (that is, one of them is removed), it is likely that one of the triggerfishes (often both) will jump out of the tank or die from stress. The fact that the initially dominant male fish retains his supremacy for only a short time may be a result of his exhausting himself during all the digging activities. If he yields in any way to his female—in other words, fails to demonstrate his supremacy without pause—then “she” may get the upper hand. This scenario may well be restricted to the aquarium; on the reef, the two fishes would simply go their separate ways. In my aquaria, Bluechin Triggers have always changed sex after a maximum of six years, and on each occasion I have then introduced as small an individual as possible as a replacement. It should be easy to establish whether matters follow the same course in other species suitable for the aquarium (for example, the Niger Trigger), albeit
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in suitably large aquaria and with the appropriate maintenance conditions! GENERAL INFORMATION ON THE TRIGGERFISH FAMILY
The triggerfishes, family Balistidae, comprise 11 genera with a total of around 40 species, and occur in all the warm seas of the world. They are, however, mainly inhabitants of coral reefs, and only a very few species live in subtropical regions or in open water. Many species are colorful, some incredibly gaudy—consider the Clown Trigger, for example. Astonishingly, in their natural habitat these bright patches of color are lost amid the equally colorful coral aquascape. Their coloration has the effect of breaking up the outline of the fish. According to Dr. Phil Heemstra of East Coast FishWatch, “The triggerfish takes its name from the locking mechanism of the stout first dorsal-fin spine and the smaller, slender second spine (the trigger). When the first spine is erected, the second spine is also pulled up and functions like a cam to wedge the larger spine in a vertical position. The first spine cannot be folded down,
until the tip of the second spine is pulled posteriorly. The family name Balistidae is formed from the genus name Balistes, which is derived from the Latin ballista, another name for the Roman catapult, in allusion to the trigger mechanism of the dorsal-fin spines.” A striking feature is the head, huge in comparison to the body, with its little eyes always glittering alertly; the mouth is terminal and small but contains very efficient dentition. Generally speaking, triggerfishes always look foreshortened and stocky and a bit head-heavy, and thus do not conform to the usual fish outline. Perhaps it is this that makes them so especially appealing? They swim by undulating their dorsal and anal fins and accelerate via powerful beats of their tails—they are r apid, agile swimmers with plenty of stamina, and require a lot of space. The triggerfish genera use a variety of hunting and reproductive strategies. Many of them (such as the plankton-feeding Niger Trigger or a number of Melichthys species) live in harems or large hunting packs, or in pairs, like the well-known Picasso Triggerfish ( Rhinecanthus aculeatus), which is frequent in all tropical coral-lagoon landscapes. In many cases they excavate pits at spawning time, lay a ball of eggs, and cover them with sand; these are often guarded very assiduously for several days by the male or female. Diving schools can tell a tale or two about the territoriality of breeding Left: the Assai or Arabian Picasso Trigger�sh (Rhinecanthus assai ) Below: Members of three related families from the Tetraodontiformes (puffer-like �shes): trigger�shes (Balistidae), box�shes (Ostracidae), and puffer�shes (Tetraodontidae)
R E L A H T . E : T H G I R , S U A H G N I B B E H . R : E V O B A
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triggers, which seem by preference to colonize the most frequently dived entry points. There are also pelagic pairs or group spawnings. Some species appear to be solitary and join with a partner only for a short time during the courtship and brood-guarding period, although in the case of pairs the more secretive, more circumspect partner may often be overlooked. In addition the species differ considerably in size: there are small, dainty, 4-inch (10-cm) species such as some Rhinecanthus, and there are meter-long giants like the Titan Triggerfish ( Balistoides viridescens). Plus, triggerfishes are generally diurnal. At night they sleep deep (and deeply) among the corals, wedged into a rocky crevice, sometimes with just t he tip of a caudalfin lobe protruding. It is supposedly impossible to pull a sleeping triggerfish out of its sleeping-hole even by force—you are more likely to pull it apart! AQUARIUM MAINTENANCE OF TRIGGERFISHES
In conclusion, here are a few concrete hints regarding the suitability of a number of triggerfishes for the aquarium. Essentially, only species that feed predominantly on plankton are worth recommending as aquarium fishes. The deep blue Niger Trigger ( Odonus niger) is very popular and attractive in its coloration, and it is also the species seen most commonly in the trade. On the reef it feeds predominantly on planktonic organisms, and occurs there in vast numbers. I n the Maldives there are veritable “curtains” of Niger Triggers, all hunting peacefully next to one another, through which one can swim—and they hardly bother to move out of the way. It is unthinkable to keep just one on its own! A group of five Nigers is a splendid sight, provided they have sufficient space: they require a really large aquarium, as they attain a good 12–16 inches (30–40 cm) in length and require feeding to match. It should not be our goal to produce dwarfed fishes through lack of food; leaving aside the animal cruelty aspect, there is no chance of maintaining these fishes in g roups or pairs. Competition for food gives rise to aggression, and that is hardly news! In addition, the adults do not develop their bright red chisel-like teeth unless they are healthy. But given the appropriate conditions, Niger Triggers are wonderful fishes to keep, rather undemanding in their food requirements (you just need to give them enough). They like plenty of current and a varied profile to the reef, but otherwise conform to the stereotype. All this applies equally to the following triggers: the Black Triggerfish (Melichthys niger), the similar but more strikingly colored Pinktail Trigger ( M. vidua), the Indian Triggerfish (M. indicus), and, especially recommended, as it is also smaller, the Bluechin Triggerfish ( Xanthichthys auromarginatus). It also applies to the fabulous Crosshatch Triggerfish ( X. mento), whose courtship and spawning behavior I never tire of watching in my aquaria. If pos-
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sible, the latter should be kept in slightly cooler conditions; temperatures of more than 79ºF (26°C) make it high-strung. Astonishingly, its cousin from the Caribbean, the Sargassum Triggerfish ( X. ringens), has quite different feeding habits: it hunts its prey near the bottom and is a sea-urchin eater. I have little experience with the genus Sufflamen, and have kept only a single Scimitar Triggerfish ( S. bursa). Though not a plankton feeder, it was rather peaceful and its main interest was only in small crustaceans—now and then it would find a freshly molted cleaner shrimp impossible to resist. All in all, however, I would advise against the maintenance of members of this genus because of their feeding habits (they are substrate hunters). Unfortunately, the loveliest of the triggerfish species also have these disruptive feeding habits. Clown Triggers (Balistoides conspicillum) really are unsuitable in many respects. They love any type of creature with spines, and it is these that are their preferred prey on t he reef as well. If you keep this fish, you must forget about maintaining sea urchins, starfishes, and sea cucumbers; even bivalves may arouse their interest. They will live in peace and harmony with cleaner shrimps, but not with all other small crustaceans or even larger crabs. They will routinely break small coral-dwelling symbiotic crabs out of the coral branches; even pistol shrimps are not always safe from them, and they may even carry off the symbiotic blenny at the same time. Sooner or later, the Clown Trigger displays its aggressive nature, often without any discernible provocation. Possibly even the biggest and best-decorated aquarium is insufficient to satisfy their urge to explore. And if they get really bored, then heaven help anything that gets in the way of their teeth! On the reef, it is very noticeable that “everyone” deliberately gives Clown Triggers a wide berth. Even very large angelfishes (such as the Blueface Angelfish, Pomacanthus xanthometopon) turn aside when a Clown Trigger comes along. I have similar reservations about the Undulate Triggerfish ( Balistapus undulatus) and also, unfortunately, the various Picasso trigger species, although the latter at least don’t grow all that huge. They may behave nicely for a long time and appear to be peaceful and well behaved, but they simply cannot be trusted! And many species just grow too large, even for a shark tank. Even there, they are not happy. Still, an aquarium with no triggerfish at all is a bit like a soup with no salt. I am happy to admit I am a trigger fan! REFERENCES
De Graaf, F. 1977. Tropische Zier�sche im Meeresaquarium. Neumann-Verlag, Melsungen, Ge rmany. Klausewitz, W. and P. Wilkens. 1979. Handbuch der Meeresaquaristik . Fische/Niedere Tiere, Vol. 3. Pfriem-Verlag, Wuppertal, Germany. Thaler, E. 1997. Leopoldine—Eine recht dumme Geschichte. Das Aquarium 12, 342:40–42.
Reef-Safe Triggers
BY SCOTT W. MICHAEL
The vast majority of triggerfishes are not the least bit suitable for the reef aquarium. Most are polyphagous, feeding on a wide array of invertebrates, including prized species that we nurture in our reef tanks. A small group of triggerfishes, however, are exceptions to this rule. These reef-tank-suitable species feed mainly on zooplankton and typically ignore invertebrates if they are fed frequently enough by the aquarist. One important caveat: they are likely to “stray” and start eating your desirable invertebrates if they are underfed. They are also prone to weight loss if not fed several times a day. The good triggerfishes for the reef tank are also less likely to rearrange the aquarium decor. This potentially destructive triggerfish behavior can lead to corals toppling over or falling on each other, causing mechanical damage and subsequent death. Some triggerfish species may leap from an open aquarium or spit water on electrical outlets. This includes members of t he genus Xanthichtys.
Pinktail Trigger�sh (Melichthys vidua)
Sargassum Trigger�sh ( Xanthichthys ringens)
Melichthys niger �BLOCH, 1786� BLACK TRIGGERFISH �BLACK DURGON�
This species is found in tropical waters around the world and is usually seen in aggregations, swimming high above the reef, often with schooling zooplankton feeders. It is also found associating with large floating rafts of Sargassum, a species of brown algae. Because it feeds mainly on floating plant material and zooplankton, it is a possible candidate for the reef aquarium. However, in nature and in captivity it will occasionally nibble on sessile invertebrates. It may also harass ornamental shrimps that are introduced after it has become adjusted to its captive home. Melichthys vidua �SOLANDER, 1844� PINKTAIL TRIGGERFISH
This attractive triggerfish is a good candidate for the reef aquarium. It is a mild-mannered fish that is even more sociable toward other fishes than most triggers (including the Niger Triggerfish). Unlike others in the reef-suitable triggerfish category, this species feeds on larger, motile invertebrates (including crustaceans and octopuses) and small fishes. It is more likely to ignore cleaner shrimps if they are introduced before it is. Odonus niger �RÜPPELL, 1837� NIGER TRIGGERFISH �R EDTOOTH TRIGGERFISH�
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This triggerfish is primarily a zooplankton feeder and it can be successfully housed in reef aquariums. That said, some have been known to feed on encrusting sponges. I have also seen the rare individual nip at snails and ornamental crustaceans. They are unlikely to harm corals. If you want to attempt to keep a shrimp with this triggerfish, add the crustacean before you add the trig-
Bluechin Trigger�sh ( Xanthichthys auromarginatus) male: some zooplanktonfeeding trigger�sh species can be kept in a reef tank.
gerfish. Provide enough meaty food to keep them from developing problematic feeding habits. Xanthichthys SPP. XANTHICHTHYS TRIGGERFISHES
These are easily the best triggerfishes for the reef aquarium. On rare occasions, these species may nip at sessile invertebrates or attack delicate crustaceans, like anemone shrimp (Periclimenes species), but most individuals will behave themselves when it comes to corals. They are rarely aggressive toward their tankmates, unless the latter are much smaller and/or introduced to the aquarium after they are. Larger individuals have been known to prey on small fishes. From The PocketExpert Guide: REEF AQUARIUM FISHES (Microcosm/TFH Professional Series)
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TRIGGERFISHES
THE SYSTEMATICS of the
Triggerfishes [ Family Balistidae] by Inken Krause
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Left: Undulate Trigger�sh (Balistapus undulatus) Below right: Two young Queen Trigger�shes (Balistes vetula) Opposite page: A pair of Bluechin Trigger�shes ( Xanthichthys auromarginatus) in a large reef aquarium
T
he triggerfish family (Balistidae) belongs to the order Tetraodontiformes, the puffers and their allies. Triggerfishes are thus related to puffers, boxfishes, porcupinefishes, and filefishes, as well as the huge ocean sunfishes (Molidae). The family contains 12 genera with some 38 species that inhabit the Atlantic, the Indian, and above all the Pacific Ocean. In addition to the triggerlike action of its dorsal fins, described previously, a characteristic of the anatomy of all triggerfishes is the rhomboidal body, which is covered in a very stiff, leathery skin. The posterior part of the body is stiff and rigid, and for this reason triggerfishes propel themselves with undulating movements of the anal and dorsal fins, which are strongly developed in almost all species. They can, in fact, attain speeds that are almost incredible, especially in the case of the large, rather plump-looking species. Many members of the family have strongly developed, chisel-like teeth with which they can effortlessly crack open the bodies of hard-shelled mollusks and spiny invertebrates such as sea urchins. Below is a list of all the genera of the family, with a summary of their ecology and peculiarities, as well as the suitability of selected species for aquarium maintenance: G E N U S Abalistes
The genus Abalistes, with its two species A. stellaris and A. filamentosus, is virtually unknown to aquarists. For a long time it was regarded as monotypic, that is, containing only one species. The type species, A. stellaris from the Indo-Pacific, attains a length of around 24 inches (60 cm), and hence is unsuitable for aquarium mainte R E T H G I
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nance unless a water volume approaching 1,000 gallons or several thousand liters is available. In addition, the species, when adult, is colored a rat her unattractive silvery gray except for the “star spot” on the dorsal region that gives the species its name. Juveniles are appreciably more attractive to look at, with a yellow to brown pattern on a light background, and thus a little reminiscent of Pseudobalistes fuscus. A. stellaris enjoys greater popularity as a food fish in the markets of Southeast Asia. The second species of the genus, A. filamentosus , wasn’t described until 2004 (Matsuura & Yoshino). G E N U S Balistapus
The only representative of the monotypic genus Balista pus is the gloriously colored B. undulatus. The Undulate Triggerfish is widespread over the entire Indo-Pacific. Thanks to its splendid appearance (bright yellow-orange stripes on a blue-green background) and its rather small maximum length of only 12 inches (30 cm), it is a popular aquarium fish. Unfortunately, however, its immense potential for aggression is often underestimated, and can greatly exceed that of some larger species. Only relatively large and aggressive fishes are suitable as tankmates. B. undulatus is especially interesting on account of its sexual dichromatism, rather atypical for the family, as adult males lack the pattern of stripes or dots above the mouth (Schneidewind 2002). Nevertheless, extreme caution is advised when attempting to keep a pair in the aquarium.
The “Trigger” Mechanism: (A) The folded down dorsal spines. (B) When the �sh becomes alarmed, it raises the very strong, tall �rst dorsal spine, which is followed by the “trigger,” a shorter, more slender second spine. (C) The locked position. Only when the second spine is relaxed can the �rst spine fold back down.
C B
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On the one hand the patterning in this species varies depending on its geographical origin, which makes unequivocal determination of the sexes more difficult, and on the other, even individuals of opposite sexes can be very aggressive towards one another.
Balistes Of the four species of the genus Balistes (B. capriscus, B. polylepis, B. punctatus, and B. vetula) only the lastnamed species, the Queen Triggerfish, is in fact relevant to the aquarium hobby. B. vetula is indeed extremely attractive because of its pretty coloration in various shades of blue, green, and yellow, but with a maximum length of 24 inches (60 cm) it is more suitable for public display aquaria. Males and females are colored essentially the same, but adult males can be recognized by their noticeably longer filaments. Divers know this species as a fierce biter when defending its nests. GENUS
Balistoides The genus Balistoides contains two species: Balistoides conspicillum and B. viridescens. By virtue of its “eccentric” coloration, Balistoides conspicillum, the Clown Triggerfish, is undoubtedly one of the most attractive fishes that the family Balistidae has to offer. The bold pattern of white spots on a midnight-black base color, along with the bright yellow lips and fin edgings, make this species a real aesthetic experience. But the Clown Triggerfish owes its popularity mainly to the black and yellow pattern on its back, which is immediately reminiscent of the spotted coat of a leopard. Because of its appearance many aquarists do not hesitate to buy this splendid fish for maintenance in the aquarium, unaware of its eventual size of up to 20 inches (50 cm), its aggressive temperament, and its family-typical liking for dining GENUS
Black Trigger�sh (Melichthys niger )
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on various spiny invertebrates and crustaceans. It has a nasty reputation for sometimes changing personalities, shifting from a good member of a community aquarium to one that viciously attacks tankmates, sometimes developing a habit of targeting its victims eyes. Balistoides viridescens (the name literally means “becoming green”), the Titan Triggerfish, can justifiably be described as the “big brother” of the Clown Triggerfish. It exceeds even the latter in size and aggressiveness. Experienced divers are fearful of accidentally encountering brood-caring pairs of this up-to-30-inch (75 cm) fish because of its readiness to attack. Further details of its unsuitability as an aquarium fish should not be necessary. Give this species a wide berth in the wild and don’t even consider it for a home aquarium.
Canthidermis The genus Canthidermis, from the Red Sea and parts of the Indian Ocean, contains three species ( C. macrolepis, C. maculatus, and C. sufflamen), which, at first glance, the layman might not recognize as triggerfishes at all. The body is unusually elongate and has an equally atypical high second dorsal and deep anal fin. In addition, Canthidermis species do not live reef-bound like their relatives, but in the open water, where they form pelagic schools (above all in the case of C. macrolepis) and follow larger predators such as sharks in the hope of eating discarded scraps of food (Schneidewind 2002). Because of their way of life, all species are unsuitable for aquarium maintenance—and also of little interest, as they have minimal aesthetic appeal. GENUS
Melichthys The genus Melichthys contains three very similar species: the Indian Triggerfish (M. indicus), the Black TriggerGENUS
Indian Trigger�sh (Melichthys indicus)
E S U A R K . I , R E L A H T . E , P O N K . D , E S U A R K . I : T H G I R P O T M O R F E S I W K C O L C
Clown Trigger�sh (Balistoides conspicillum)
Niger Trigger�sh (Odonus niger )
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Rectangular Trigger�sh (Rhinecanthus rectangulus)
Assasi or Indian Picasso Trigger�sh (Rhinecanthus assasi )
fish (M. niger), and the Pinktail Triggerfish ( M. vidua). With a maximum length of less than 14 inches (35 cm), all are relatively small, and all are characterized by a rather nondescript dark base color, which probably serves as camouflage when they leave the shelter of the reef to hunt for food in open water. But in shallow water and in bright light (for example in an aquarium with HQI or T5 lighting), a fine, sometimes very attractive pattern becomes visible in all three species. A characteristic feature of the genus is an upward-pointing mouth, which identifies the species as a planktonfeeder. But they will ingest macroalgae and floating plant material (especially in the case of M. niger) and sometimes form loose groups to hunt for food. Spiny invertebrates and crustaceans, which figure on the menu of the majority of triggerfishes, are almost never harmed, even in the aquarium. Hence the species of the genus Melichthys are appreciably better suited to aquarium maintenance than the majority of other balistids. They are deserving of more attention.
appropriately known as the Redtooth Triggerfish, as the majority of specimens (albeit not all) possess characteristic angular red teeth that are used above all to scrape sponges and similar growths from rocks, but hardly ever to prey on larger invertebrates. Like the members of the genus Melichthys, O. niger has an upward-pointing mouth, which characterizes plankton-feeding species. This species, too, forms loose feeding groups, often containing very large numbers of individuals, to hunt macroplankton in the open water. This circumstance even permits the maintenance of the Niger Triggerfish in reef aquaria, as attacks on any invertebrates they contain are most unlikely. But one should not forget the adult size attained, which can reach up to 20 inches (50 cm). Anyone who has once seen the imposing sight of full-grown O. niger in its natural habitat is unlikely to countenance the idea of keeping such a fish in a normal-sized aquarium, and will have no time for those aquarists who deprive the juveniles imported as “baby triggers” of the chance for natural development.
G E N U S Odonus
The genus Odonus contains only one species, namely the Niger or Redtooth Triggerfish (O. niger), which, however, is probably better known among aquarists than any other triggerfish. O. niger is one of the species that most frequently find their way into marine aquaria. Although its scientific name would suggest otherwise, O. niger is not, in fact, black, but dark blue, sometimes with a greenish sheen. The precise color and the stripe pattern on the head vary within its vast distribution in the IndoPacific, from the Red Sea to Polynesia. The species looks really black only in the blue twilight at great depths, or when preserved in alcohol. In Germany O. niger is more
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G E N U S Pseudobalistes
The three species of the genus Pseudobalistes—Yellowmargin Triggerfish (P. flavimarginatus), Bluelined Triggerfish (P. fuscus), and the Stone Triggerfish ( P. nau fragium), are, at up to 24 inches (60 cm), among the largest members of the family Balistidae. In practice, only P. fuscus is occasionally available in the aquarium trade, a fact that is linked on the one hand to its attractive coloration and on the other to the droll appearance of the juveniles that are often imported at a tiny size. The species usually lives solitarily over expanses of sand in the reef areas of the Indo-Pacific (above all the Red
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Scimitar Trigger�sh (Sufflamen bursa)
P O N K . D : T F E L M O T T O B , R E L A H T . E : T H G I R D N A P O T
Sea) and is sometimes found in lagoons. Juveniles of P. fuscus, which have dark spots on a yellow and white background, are colored quite differently from adults, which are no less beautiful with their bright blue stripes on a yellow base. Even though it is all too easy to buy the comical little juveniles on impulse, none of the species of the genus can be recommended because of their size and their potential for aggression. G E N U S Rhinecanthus
The genus Rhinecanthus comprises seven species, but only the two known as the Picasso Triggerfish ( R. aculeatus) and the very similar Assasi Triggerfish ( R. assasi), and very rarely the Halfmoon Picassofish ( R. lunula), Picasso Trigger�sh (Rhinecanthus aculeatus)
play a role in the marine aquarium hobby. The origin of the name will be obvious to anyone who has seen one of these fishes with its colorful, abstract geometrical lines on a light background. Post-larval juveniles are uniform gray in color up to 4 cm long and only then take on the remarkable coloration of their species. Rhinecanthus aculeatus is distributed across the entire Indo-Pacific region, with the exception of the Red Sea and the Arabian Gulf, where the species is replaced by the endemic (and very similar) species R. assasi. Both live over sandy substrates, in lagoons, and on reef flats, where they feed on a wide variety of invertebrates (and sometimes also small fishes), which, when necessary, are extracted from the sandy bottom in the triggerfish-typical manner, by “puffing.” With a maximum length of 12 inches (30 cm), both species are not only popular for aquarium maintenance, but also eminently suitable as long as an adequately large aquarium (1,500 liters upwards) is provided and they are not housed with potential prey (spiny invertebrates, small crustaceans, or small fishes). G E N U S Sufflamen
The genus Sufflamen contains five species that are distributed mainly in the Indo-Pacific. Externally they exhibit close similarities to the species of the genus Rhinecanthus. Like the latter, they are relatively small and attain less than 12 inches (30 cm) in length. Suf flamen species are essentially rather soberly colored and Bluelined Trigger�sh (Pseudobalistes fuscus), juvenile
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,
SYSTEMATIC OVERVIEW OF THE
Trigger�sh Family [Balistidae]
Within the order Tetraodontiformes (puffers and their allies), the triggerfishes constitute the relatively small family Balistidae, with at present 12 valid genera to which a total of 38 species are assigned. This should in no way be regarded as static. The systematics of the triggerfish family, like those of many other fish families, are subject to change, and new species have been described in recent years, for example Abalistes filamentosus in 2004 (Matsuura & Yoshino, 2004). Even though it is not always easy to comprehend the details of their systematics, thanks to a number of characteristic features even the layman can generally immediately recognize a triggerfish as such. —Inken Krause
GENUS Abalistes �2�
GENUS Pseudobalistes �3�
A. stellaris A. �lamentosus
P. �avimarginatus P. fuscus P. naufragium
GENUS Balistapus �1�
B. undulatus GENUS Balistes �4�
B. capriscus B. polylepis B. punctatus B. vetula GENUS Balistoides �2�
B. conspicillum B. viridescens
ON THE INT ERNET
GENUS Canthidermis �3�
(6-22-08), FishBase: http://www.�shbase.org/Summary/ FamilySummary.cfm?Family=Balistidae
C. macrolepis C. maculatus C. sufflamen
Clockwise from top left: Deep-Sea Trigger�sh ( Xanthichthys mento), Blue -Throat Trigger�sh ( Xanthichthys auromarginatus), Picasso Trigger�sh (Rhinecanthus aculeatus) being cleaned by the Whitebanded Cleaner Shrimp ( Lysmata amboinensis), Sargasso Trigger�sh ( Xanthichthys ringens),
GENUS Melichthys �3�
GENUS Rhinecanthus �7�
R. abyssus R. aculeatus R. assasi R. cinereus R. lunula R. rectangulus R. verrucosus GENUS Sufflamen �5�
S. albicaudatum S. bursa S. chrysopterus S. fraenatum S. verres GENUS Xanthichthys �5�
GENUS Odonus �1�
X. auromarginatus X. caeruleolineatus X. lineopunctatus X. mento X. ringens
O. niger
GENUS Xenobalistes �2�
M. indicus M. niger M. vidua
X. tumidipectoris X. punctatus
P O N K . D , T
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hence of little interest to aquarists. This is probably the reason why most of the species of the genus are rarely seen in the trade, apart from the Halfmoon Triggerfish (S. chrysopterus), which is somewhat more popular. This species is chiefly interesting because adult males can be identified by their blue chest and throat region, lacking in juvenile and female individuals; the species thus exhibits sexual dichromatism. G E N U S Xanthichthys
The genus Xanthichthys is very interesting for the aquarist with its five species: the Bluechin ( X. auromarginatus), the Bluelined ( X. caeruleolineatus), the Striped ( X. lineopunctatus), the Crosshatch ( X. mento), and the Sargassum Triggerfish ( X. ringens). In particular, X. auromarginatus enjoys considerable popularity in the aquarium trade. On the one hand, all the species remain small enough, at 8–12 inches (20–30 cm), for maintenance in larger aquaria; on the other, like their relatives in the genera Melichthys and Odonus, they live a planktivorous existence and, with their upward-pointing mouths, are not inclined to dine on large invertebrates. The genus is, however, also interesting by virtue of the marked sexual dichromatism that occurs, at least in the three species mentioned. Thus, for example, male individuals of X. auromarginatus have a blue throat and yellow fin edgings, while the females are uniformly silvery gray. Thanks to this characteristic, there is no problem at all in putting together pairs for aquarium maintenance, and they always tolerate one another well, even though in the wild they can be seen living together in loose groups. G E N U S Xenobalistes
The genus Xenobalistes (Matsuura, 1981) is the youngest within the family Balistidae, and to date includes only two species: the type species X. tumidipectoris, which was described on the basis of a single specimen found in the stomach of a Blue Marlin, and X. punctatus . Extremely unusual in the triggerfish family, X. punctatus looks rather like a boxfish when viewed from the front, more like a triggerfish in the lateral view. REFERENCES
Schneidewind, F. 2002. Drücker�sche. Tetra Verlag, Bissendorf, Germany. Nelson, J. S. 1994. Fishes of the World , Vol. 3. John Wiley & Sons, Hoboken, NJ. Pp. 445–446. Kuiter, R. and H. Debelius. 2006. Atlas der Meeres�sche. Kosmos-Verlag, Stuttgart, Germany. Matsuura, K. 1981. Xenobalistes tumidipectoris, a new species and genus trigger �sh (Tetraodontiformes, Balistidae) from the Marianas Islands. Bull Natl Sci Mus (Ser. A) (Zool.), 7 (4):191–200. Matsuura, K. and T. Yoshino. 2004. A new t rigger�sh of the genus Abalistes (Tetraodontiformes: Balistidae) from the western Paci�c. Records of the Australian Museum 56 (2): 189–194.
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MADAGASCAR A
T R E A S U R E
I S L A N D
by Marlen Hundertmark and Christian Hepperger
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I N D I A N
O C E A N
From legend and old stories, many people know Madagascar as an island of pirates and treasure. In the past there was indeed much hunting and digging for treasure there, but after a firsthand look for ourselves, we were left with the impression that the real treasures of this island definitely lie somewhere else: in its unspoiled nature and its unique and ancient wildlife. Madagascar is the fourth largest island on Earth and is also sometimes called The Sixth Continent. Because of its separation from Africa 150 million years ago and its subsequent long isolation, unique flora and fauna, unequalled anywhere else in the world, have evolved there, both on land and in the water. For this reason we decided to spend six weeks experiencing this unique natural history for ourselves. Following our arrival in the capital, Antananarivo, and a visit to the Andasibe nature reserve, where we managed to find amphibians, reptiles, and lemurs, above all the Indri—not a particularly difficult feat, given its shrill cries—we eventually traveled to the sea. In view of the political situation in the country caused by an impending presidential election, we were at pains to avoid problem areas and take the quickest route to our first objective, the Masoala Peninsula in the East of Madagascar. We decided against whale watching, an activity that had figured quite high on our wish list; given that we were going to be there, we really wanted to make the most of the opportunity. But the political situation simply didn’t allow it, so we took
The big feed: a group of Monk Tangs ( Acanthurus gahhm) with a Zebrasoma desjardinii and a parrot�sh
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A pair of Melon Butter�y�shes (Chaetodon trifasciatus) in their land of milk and honey
Chevron Butter�y�sh (Chaetodon trifascialis)
a rattly old plane to Maroantsetra, a lonely little town on the edge of the Masoala National Park. From there we continued our journey by boat in order to penetrate further into the Masoala rainforest. WHALE DAY
During the roughly two-hour boat journey, we paused for a fairly long time as a mother whale and her calf suddenly surfaced close to our boat! At first we were terrified by the presence of the dark colossus close to our little cockleshell, but after the initial shock had worn off we enjoyed the encounter. The two whales swam around near us for quite some time; having had to pass up the
Scrawled File�sh ( Aluterus scriptus )
opportunity to go on a whale watching trip, we were exceedingly happy that the whales had apparently come looking for us! During the rest of the crossing we saw even more of these marine mammals, although they passed us by at a greater distance. The next morning we went into the water for the first time, prepared to meet anything, and we were hardly worried at all when, again, a gigantic whale surfaced only around 50 meters away. We made our way across small meadows of seagrass to the colorful gardens of coral. A striking feature of this area was the presence of truly enormous large-polyp stony corals in a variety of colors—chiefly brain corals, but there were also great
Giant Clam (Tridacna maxima)
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Now and t hen we e ven encountered
T U R T L E S
A N D
D O L P H I N S ,
which served to confirm further the impression of an unspoiled underwater world...
Sudden close encounter with sea turtle
expanses of Acropora species and other small-polyped genera. In addition we saw splendid giant clams, which the people of Madagascar like to eat, hence the empty mollusk shells found all over the beaches. The fishes that live here really are dwelling in paradise. They swim around in a regular soup of plankton, surrounded by an unspoiled coral landscape that offers innumerable hiding places. But that was precisely what made it difficult for us to watch them, as they would rapidly disappear beneath a rocky overhang, into a crevice, or among the dense branchwork of the corals. Apparently they weren’t used to visits from divers with bubbling breathing apparatus or snorkelers with paddling fins. For this reason we tried to move as quietly as possible. But we nevertheless had the impression that the fishes here were considerably more circumspect than in other places where we have snorkeled. Everywhere we went, at best we saw them peering out of their hiding places and eyeing us with considerable suspicion. Butterflyfishes, wrasses, the blue and yellow Longnose Filefish ( Oxymonacanthus longirostris), and even the normally rather aggressive damselfishes—all preferred to swim out of our way. The only fish on which we had little effect was the huge Napoleon Wrasse. The underwater world of Madagascar is astonishingly unspoiled. Two years previously we had been in
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the Seychelles and had seen dramatic evidence of the effect of the climatic phenomenon El Niño. It was only the direct comparison that truly brought home to us how severe the damage in the Seychelles had been, and we hope that the coral reefs of Madagascar will remain unaffected by such dramatic influences. What particularly fascinated us was the proximity of this marine biotope to the undisturbed jungle, so that the two most species-rich habitats on our planet— coral reef and rainforest—practically bordered on one another. We found this intense experience of nature truly unforgettable. We would recommend this exceptional place of forests—and water—to anyone who loves nature, enjoys adventure, and is not too concerned about comfort. Madagascar also has something to offer to those who don’t like doing without electricity and hot water, but they would do better to stick to the West coast, where there are areas that are better equipped to welcome tourists. THE WEST COAST
After another uncomfortable flight over the rainforest and an 11-hour ride in the cargo space of a very old, beat-up truck, we reached the boat to the island of Nosy Be. (It should be mentioned that in those 11 hours we traveled barely 68 miles—110 km). The roads—if you can
Brightly-colored Acropora stony corals
call them that—are generally in catastrophic condition and sometimes barely negotiable, but they are noticeably better in the West than in the East. Driving slowly, we should admit, has its upside: during this journey we saw lots of chameleons and Phelsuma species (the large day geckos) by the side of the road. Nosy Be is an island off the Northwest coast of Madagascar and was to be the starting point for our proposed sailing trip. We sailed south along the coast to seek out the finest areas for snorkeling. The reefs of the islands that lie offshore along the West coast of Madagascar represent a fantastic experience for any marine aquarist, and a significant advantage of such a boat trip is that you have immediate access to the diving or snorkeling site—straight from the ship. A multitude of brilliantly colored fishes were disporting among the corals: grammas, anthias, wrasses, filefishes, tangs, and rabbitfishes as well as big fishes— everything the aquarist’s heart could desire. There were also numerous butterflyfishes, for example Chaetodon madagascariensis, C. lunula, and C. trifasciatus, frolicking among the corals and here and there nipping at the polyps. Pairs of Moorish Idols ( Zanclus cornutus), and bannerfishes such as Heniochus acuminatus (again in pairs) swam repeatedly to and fro across the reef. Here and there we saw single large barracudas holding posi-
tion in the current, giving us reason to pause. There were coral gardens as far as the eye could see. Soft and leather corals grew next to blocks of Porites, surrounded by colorful sponges, gorgonians, Seriatopora and Montipora stone corals, brain corals, and expanses of sea anemones in which innumerable Skunk Clownfish ( Amphiprion akallopisos) were frolicking, and in between them growths of Acropora with the diameter of a two-bedroom house—and all this in the loveliest colors imaginable. Giant clams and a huge variety of other sessile inhabitants of the reef were also here, in a wealth of species that took our breath away. Now and then we even encountered turtles and dolphins, which served to confirm further the impression of an unspoiled underwater world, but sometimes also gave us a tremendous shock—as when a group of 20 dolphins suddenly appeared from out of the deep blue of the ocean. During this sailing trip we snorkeled countless times, each session being quite unique and often lasting longer than the captain of the boat would have preferred. Unfortunately these days at sea sped by faster than we would have liked, so we were soon sailing back to the main island of Nosy Be. We spent one more final day there, reviewing our experiences of the past weeks, and agreed that Madagascar is one of Earth’s most fabulous destinations.
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N
ot long after my Complete Illustrated Breeder’s Guide to Marine Aquarium Fishes was released, I was confronted by people asking, “Why aren’t mandarins in the book?” My answer was quite simple: I never really thought about it. In fact, I realized that I had been shunning mandarins for many years. When I was 12 years old I set up my first marine aquarium. I was determined to fill the system with bold and beautiful colors from around the world, and my eyes were quickly drawn to a fish with fluorescent stripes and swirls of green and blue. As I watched the bright blue pectoral fins undulating wildly against the bright orange background color and t he long dorsal fin flashing high above the body, I was won over: I purchased my first Green Mandarin, Synchiropus splendidus. Within days the subject of my fascination was showing signs of stress as he
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Breeding
Mandarins story and photos by Matthew L. Wittenrich
tirelessly hunted the captive reef for prey. Days and weeks went on as he grew thinner and ever more emaciated. My most-prized fish slowly wasted away, then died. NEW HOPE FOR A STAR�CROSSED SPECIES
After a 14-year hiatus, I must admit that the mandarins I had been boycotting are slowly creeping toward the top of my list of favorite fish. Mandarins, or dragonets, are among the most beautiful and graceful marine fishes encountered in the aquarium trade, offering bold and exciting colors and contrasting patterns that seem to wave and roll as they hover above the reefscape. Unfortunately, the Green Mandarin, and its congener the Spotted Mandarin, S. picturatus, exhibit one of the highest rates of mortality among captive marine fishes. Until a few years
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ago it was a challenge to keep one alive for more than a few months. Due to their tiny mouths and strong preference for small, live crustacean prey, mandarins are difficult to feed in aquariums and most suffer from starvation. Today, dedicated hobbyists are teaching their mandarins to accept frozen and even pelleted foods and, with a bit of patience, mandarins are no longer a “for experts only” fish. BREEDING MANDARINS: MY WHY
Noted reef aquarist Julian Sprung first raised a single Green Mandarin in 1989, and a handful of aquarists have since reported limited success. I had heard various reports of European aquarists raising a few mandarins and even tracked down a copy of Wolfgang Mai’s article in CORAL magazine (Vol. 1:2) about his successful journey with Spotted Mandarins. These initial successes, coupled with my concern about the methods used to capture wild mandarins, prompted me to begin experimenting with new rearing techniques and foods in early 2008. Highly cryptic and crepuscular in nature, mandarins are captured for the aquarium trade using slingshotstyle mini-spearguns constructed from local bamboo. Pulling back on a thick rubber band, divers fire long, double-pronged needles into the sides, belly, or tail of the fish. When speared in the posterior portion of the body, and assuming the spears do not damage vertebrae, there are no long-term consequences. Missing vertebrae and visceral punctures, however, create immediate or delayed risk of mortality. The fishery for mandarins is highly selective, targeting large males. According to the work of Yvonne Sadovy, a research scientist at the University of Hong Kong, Green Mandarins congregate nightly at designated spawning sites on the reef. Here, females select the largest males to mate with. As the large males are removed for the aquarium trade, females are forced to mate with smaller males. Sadovy’s observations suggest that as females mate with smaller, less experienced males, spawning ascents become awkward and prolonged, which renders the pair more prone to predation.
BROODSTOCK BASICS
Perhaps the largest hurdle to breeding mandarins is the difficulty of obtaining healthy broodstock. I choose full-bodied specimens that seem alert and active. Wild mandarins are starved through the transport chain and are generally emaciated, often beyond the point of no return, by the time they reach retail outlets. Bringing a badly emaciated mandarin back from the brink is a definite challenge and without sufficient quantities of live mysis shrimp, I have always lost this battle. Even badly emaciated mandarins with pinched bellies will pick at the substrate and seem alert to food stimuli, but without high protein, lipid-rich food in sufficient quantities, most will certainly perish. Many aquarists report that heterosexual pairs confined in aquariums quarrel tirelessly. Males most often antagonize females, but many times females become the aggressors. These situations almost always arise from insufficient food and poor body condition. Though reproduction is a strong driving force in the lives of mandarins, feeding comes first. Mandarins will defend feeding territories aggressively when food is scarce. In such cases, it is not unusual to see pairs of newly acquired mandarins fighting. This behavior quickly subsides once the fish are properly fed. SECRETS OF MANDARIN FEEDING
To thrive in a captive environment, mandarins must be supplied with sufficient high-protein foods. Of the two common feeding methods, one certainly produces better long term results. It has long been said that in order for mandarins to survive, a large, mature, rock-filled aquarium is needed—the idea being t hat harpacticoid copepod populations present on a large surface area of live rock will support the near-constant foraging behavior of this fish. While this method can support the dietary demands of a mandarin, it is far too prone to failure in closed systems. (Aquarists often overestimate the productivity of their reef systems or stock species that compete for the limited crops of microfauna.) Refugiums help support copepod populations, but all too often
Previous page: One of the author’s male broodstock Spotted Mandarins (Synchiropuspicturatus) Left: Male Green Mandarins (Synchiropussplendidus) displaying to a nearby female in the author’s breeding aquarium Right: At 10 months of age, this captive-raised pair of Green Mandarins exhibits sexual dimorphism.
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A handful of juvenile Green Mandarins at three months, from the author’s �rst successful rearing. Right: A mixed cohort of captive-raised mandarins fully trained to accept prepared foods, making the challenge of successfully feeding these species a thing of the past.
mandarins slowly starve in such settings. A much more realistic and successful approach involves weaning mandarins off a strictly live-food diet and teaching them to accept frozen foods that are readily available, such as mysis shrimp. (Piscine Energetics is the brand I trust most.) Matt Pedersen of MOFIB (Marine Ornamental Fish and Invertebrate Breeders) developed a simple way to do this: isolate new mandarins in suspended breeder baskets (or small quarantine tanks) and get them feeding on enriched live brine shrimp. Then introduce frozen brine shrimp and mysis shrimp. After the fish begin sampling the frozen fare, gradually withdraw the live diet. Once they are eating frozen fare with vigor they are released into the display tank, where their “training” pays off. Once conditioned and eating prepared foods, pairs of mandarins require little environmental stimuli to begin spawning. I prefer to use two-bulb lighting fixtures with “bright” and “actinic” bulbs that mimic dusk and dawn. While this is not necessary to trigger spawning, it allows you to set your clock according to nightly spawning events—and the sight of a pair rising into the water column and casting hundreds of eggs towards the surface is amazing. F E E D I N G A N D R E A R I N G T I N Y L A R VA E
While breeding and raising coral-reef fishes in captivity has become a popular aspect of the hobby over the past few years, and the number of successfully raised species continues to increase dramatically, we have yet to develop the best methods of rearing delicate larval forms. The research and development that is needed to bring new species to market is most often hindered by an incomplete understanding of a species’ life history requirements. As culturists, we have come to appreciate the diversity of larval forms in marine fishes, and realize that not all larvae are created equal. The techniques we employ to feed and raise different species should be modified to accommodate these variations. Mandarin eggs are clumped together at first, and break apart as they swell with water. They measure
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roughly .8 mm in diameter and hatch after 13 hours into oblong prolarvae with huge yolk sacs. No oil globule is present, and they have no eyes or mouths, no digestive tracts, and no fins. Two days after hatching, the larvae transform from oddly shaped yellow blobs into more streamlined shapes that slightly resemble larvae. Dragonets are known to produce some of t he smallest larvae in the ocean. While this may seem intimidating to would-be breeders, the larvae are surprisingly capable hunters. On day three or four after hatching, the larvae have grown to nearly 2 mm in total length. Mandarin larvae are tiny, but they are beautiful. Their eyes shine bright silver and their bodies bright yellow.
Their mouths are open and they are ready to feed. Larval mandarins are not active swimmers and prefer to remain stationary in slow-moving currents. It is amazing to watch such small fish curl into S-shaped patterns and pounce forward at rotifers and copepods. On day five after hatching, the larvae of Green Mandarins transform from small yellow missiles to chunky, bright, almost fluorescent orange carrots. Every one of them is visible through the green-tinted, phytoplanktondosed water. Their movements are slow and deliberate and simply stunning to watch. Instead of turning bright orange like the Green Mandarins, Spotted Mandarins turn a dirty orange or rust color with white spots on the
dorsal and ventral fin-fold. An interesting aspect of development in both species is the total lack of pigmentation on the posterior fin-fold. Over the coming days, their bodies thicken and their heads become broad. At about 10 days after hatching for Spotteds and 16 days for Greens, the larvae begin to settle on the sides of the tank, occasionally swimming around in search of food and a new place to rest. By day 15, most larval Spotted Mandarins adopt this intermittent settling behavior, whereas Green Mandarins exhibit this behavior until day 20. Their bodies turn a tan and mottled pattern and their pelvic fins are well adapted for “hopping” on the bottom. At 4 mm in total length,
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achieved at around day 17 for Spotteds and day 25 for Greens, the little mandarins are perfectly suited to life on the bottom. Their coloration makes them blend in perfectly with a sand or rubble substrate and their small protrusible mouths are ideal for snatching small copepods from the complex substrate. By day 40 they begin to slightly resemble their parents, and by day 50 both species exhibit an intricate pattern of green and brown. Green Mandarins appear in colors of mottled browns, whereas Spotted Mandarins take on drab olive tones. Juvenile mandarins greedily devour newly hatched Artemia and other microfauna lurking on the bottom of the rearing tanks, but to benefit the aquarium hobby and their keepers they need to be trained to accept prepared foods. With a bit of patience all captive-raised mandarins can be taught to do this. Like most micropredators, they seem to home in on movement. The largest hurdle is getting them to accept something that lies still on the bottom. Once they come to recognize still matter as food, the rest is easy. Pulverized pellets and Rod’s Food seem to be their favorites. DIVERSITY AND THE NEXT GENERATION
Much of a species’ popularity in the aquarium trade arises from mutation or morphological variation. Whether these mutations are naturally occurring or are achieved through selective breeding, they form the basis of a huge surge in the popularity of certain species. The patterns, colors, and variation we see in a given group of offspring are regulated by an enormous number of genes and environmental regulators. Diet and nitrogenous waste buildup are the major causes of undesirable mutants with stunted heads and deformed bodies, but desirable offspring with a misplaced stripe or brighter body coloration are just as common. The frequency with which we observe these desirable traits is usually limited by our success as culturists. If we are only successful in bringing five percent of larvae through to metamorphosis, our chances of observing oddities is drastically reduced. With mandarin survival in my own aquarium reaching 90 percent, I was sure I would observe some variation, but just how much was quite surprising. Two of the most intriguing sources of diversity were pattern and body color. No two individuals were patterned alike, and in most fish each side contrasted to the other. The turquoise and green swirls on the sides of the Green Mandarins would form intricate honeycomb grids on some, figure eights on others, and perfect exes on a few. Males seemed to have vertical dotted lines while females seemed to display the handiwork of a creative artist. Could these be designer mandarins, and could we isolate some of these intricate patterns and enhance them in future generations? Of course! One of the most desirable natural variations of Green Mandarins seen in the trade is the so-called red morph. With a distinct reddish or orange body color, this vari-
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Captive-raised Green Mandarins exhibit tremendous diversity of color and pattern. These two are eight months old and fully colored.
ant is quite popular and extremely attractive, though not much is known about it. Some anecdotal information suggests it originates from a handful of islands in the Philippines. After observing hundreds of captive-raised mandarins from many different pairs, however, I believe this is probably an example of variation within a species rather than a distinct geographical morph. Most of the juvenile Greens exhibit an overall greenish or blue hue, but some—a minority for sure—are bright red with turquoise swirls that seem to jump from the body. These are
my favorites. There are also dark blue ones that seem to blend monochromatically with their blue swirls. Perhaps my greatest excitement about mandarins came from a little yellow Spotted Mandarin. At four months old, when all his siblings were fully adorned in mint green and orange suits, this little mandarin remained the color of mustard. Today, at about ¾" long and six months old, he still has refused to go green. While designer mandarins might be a few years away, there is no doubt that captive breeding of t hese in-
credible fishes offers a boundless source of enthusiasm. Captive-raised mandarins that dine on prepared foods are ambassadors for their species, and the select few on display at the Smithsonian will teach responsibility, sustainability, and conservation to millions of visitors ever y year. For me, there is nothing so r ewarding as standing in front of one of the nation’s preeminent reef aquariums and watching as visitors get excited about seeing some of the first captive-raised mandarins ever to be shown to the public.
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Panoramic view of the estuaries and coral reef displays in the new Sant Ocean Hall at the Smithsonian’s National Museum of Natural History. Below: A bird’s eye view of the 2,000-gallon living coral reef designed by Jeff Turner—the Sant Hall’s only living display.
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Mandarins story and photos by Matthew L. Wittenrich
n September 27, 2008, the new Sant Ocean Hall, created in partnership with the National Oceanic and Atmospheric Administration (NOAA), opened at the Smithsonian’s National Museum of Natural History in Washington, DC. According to the Smithsonian’s press release, “The Hall’s combination of 674 marine specimens and models, high-definition video experiences, one-ofa-kind exhibits and the newest technology allows visitors to explore the ocean’s past, present and future as never before.” A 24-foot-long giant squid and a model of Phoenix, a 45-foot-long North Atlantic Right Whale, are among the largest and most visual displays in the museum’s 23,000-square-foot arena. Just around the corner, a 2,000-gallon living coral reef—the hall’s only living exhibit—stops onlookers in their tracks and keeps them mesmerized. Nearly five years ago, Jeffrey Turner of Reef Aquaria Design in Coconut Creek, Florida, was tasked with creating an icon. Today, his vision, a delicate balance of living corals, beautiful reef fishes, and invertebrates, is separated from an estimated seven million newly crowned reef ambassadors a year by an eight-foot-high curved glass wall. The Smithsononian’s exhibit is a major sym-
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bol of reef conservation, featuring over 100 specimens of aquacultured corals and fishes and connecting both the beauty and plight of a little-known world to a truly enormous audience. It is fitting that here at the Smithsonian, where major goals include inspiring curiosity in visitors and teaching them about the natural world, captive-raised mandarins are now on public display for the first time. I carefully stowed a dozen eight-month-old mandarins (including some juveniles with elongated dorsal fins) in a suitcase and checked them in at the Fort Lauderdale airport. Six hours later the little mandarins were immersed in a completely new world in Washington. Although mandarins are hugely popular in the aquarium trade, we know surprisingly little about their life in the wild. Mandarins and other callionymids produce some of the smallest larvae in the ocean, making it extremely difficult to observe them. When mandarins emerge from their egg cases they are a mere 1.5 mm in total length. After a few weeks in the open ocean they have grown to 4 mm (the size of a newly hatched clownfish) and are ready to settle to the lagoon floor. They easily pass through the mesh of most sur vey nets, and spotting a 4-mm-long mandarin on the complex mosaic of the reef is like finding a needle in a haystack. Identifying recruitment and population trends has been all but im-
at the Smithsonian possible. Aspects of a fish’s life history, such as growth rate, time to maturity, morphological plasticity, and larval characteristics, are taken for granted in many species, but our knowledge about mandarins is ver y limited. Captive-raised mandarins may answer many important questions. With their conservation status in question, the mandarins at the Smithsonian have offered tremen-
dous insight into the life history of the genus. Two months after the mandarins were introduced to the living reef, Joe Farmer of Reef Aquaria Design noticed that each evening, as dusk approached, one large male and up to three smaller females would congregate at a prominent outcropping on the reef. The male would stretch his fins and circle the females in a proud posture as the females reciprocated and entered the winding dance. While no spawning has been witnessed, this is what mandarins do in the wild. Throughout the day the captive mandarins are cryptic and peruse the reef singly in search of food, congregating at dusk for courtship. It is truly an incredible opportunity to have such a large and beautiful aquarium where natural behaviors can be observed. The Smithsonian may very well become home to the second generation of captiveraised mandarins, providing a firm foundation for education and conservation.
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“NO RISK, NO FUN”
?
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Thinking twice about how to stock a reef aquarium
T
story and photos by Professor Ellen Thaler
here is no doubt that the saying “no risk, no fun” has a far-reaching influence on our lives, at least for adventuresome, lively, active, and flexible people. It is the modern trend in extreme sports and investing and adventure travel, and that may be well and good, but risk too much and there will be a price to pay. This may not be a bad thing, as long as you enjoy yourself in the process and it doesn’t adversely affect you or others. But never in my wildest dreams did I imagine that this saying could be applied to the aquarium hobby. It happened like this: a colleague told me that he had just bought two Green Mandarinfishes, Synchiropus splendidus . His tank had been running—after a fashion—for only about two months. I don’t like to appear to be a know-it-all, so I gulped briefly and remarked, quite casually, that this purchase seemed a bit premature. His reply? See the title of this article. I became less gentle, pointing out that he was dealing with living creatures. He repeated the saying and looked at me as if I had said something totally unreasonable. Aquarists may well wonder whether he got any enjoyment from watching his mandarins slowly starving to death.
Pair of Green Mandarin�shes (Synchiropus splendidus) during courtship, male with erect dorsal �ns. Opposite page: A species-rich and well-fed coral-�sh community, peacefully grazing algae.
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Pair of Chelmon rostratus, �ghting with dorsal-�n spines spread; in the picture on the opposite page, the two �shes are feeding peacefully next to one another.
“IMPOSSIBLE SPECIES”
I love fishes—not just my own, but fishes in general. So I took a deep breath and was about to let loose one of my usual tirades. But when I thought about my Twinspot Gobies, my Orangespotted Filefishes, and my Sea Moths, I swallowed my words. Anyone who knows me is aware that my aquarium experiences haven’t been a bed of roses, especially when it comes to the three groups mentioned, as there is still much to be learned about their behavior. But fishkeeping isn’t something I do just for pleasure and amusement; I do it out of scientific interest and with the knowledge that, given healthy wild stock and sufficient dedication, even these difficult or “impossible” species can generally be kept in an appropriate manner and for many years. Is that any justification for experimenting with them? Certainly, even for me and my guilty conscience. Others, I openly acknowledge, see no justification for ever risking a fish life. But, leaving aside this darker aspect of my involvement in the aquarium hobby, there is food for thought here, and quite a bit can be said on the topic of “Fishes: no risk, no fun.” In 1995 I published a book, Fische Beobachten (Fish Watching), on the subject of the aquarium hobby needing to be more than just a way to satisfy our desire to stare at one yellow fish, one red fish, and one blue fish conveniently located behind glass. I have tried to encourage the idea that a tank should house at
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least two yellow, two red, and two blue fishes to make the fishes happy (although when all is said and done, even this tiny step seems to be too much for many people). In 1997 I went into the basics of this problem in an article, “Fischpolemik” (Fish Polemic), which made me a lot of enemies (but perhaps also a few friends). I thought that overall I had brought about something positive, a new way of looking at things, but since then I have become less sure. The marine aquarium hobby is now heading down a completely different path. Trifles such as the question of whether one should keep one or two (or more) specimens of a particular fish species are too seldom considered, or when they are, it is among over-cautious novices, stony-coral freaks worried about elevated phosphate levels, or old-timers who genuinely know all their fishes as individual “personalities.” The current trend I see in Europe is towards mega-aquaria, and for those one buys at least a dozen of everything—otherwise there won’t be enough color. For some, the fishes are only a moving filler element—“ornamental fishes.” This term is perhaps quite appropriate for a tank containing a gaudy profusion of corals in a disorganized jumble. Because most aquarists don’t know their fish personally (only one or another over-priced coral), they think nothing of thinning out to produce particular color nuances— for example, culling all but five out of an original 50 Yellow Tangs, or all but 10 of an original 200 Purple Anthias—and immediately replacing them with 50–200 of another species. No risk, no fun! For certain aquarists, profusion is the name of the game. At first glance these huge, modern aquariums appear to be brightly colored, completely intact, trueto-nature underwater landscapes. But if one is present at feeding time, a rather different picture emerges—one resembling the ritual feeding of the piranhas in a public aquarium. But that too can be excused as “nature, pure and simple”—including when a large fish makes a meal out of some insufficiently circumspect smaller individual. FISHY ASSERTIONS
I know that there are aquarists who are well informed and capable of thinking for themselves. They don’t even need to be as contrary-minded as I am. But perhaps it is time once again to roll out the so-called “fish polemic,” as it seems to me that a lot of the basics are still being ignored. I would like to put forward for discussion a number of assertions that continue to be made in the literature and on the Internet, but usually starting here, on paper—which may not be as convenient as website information, but is more permanent. And note that we
are talking about coral reef fishes here, that is, inhabitants of tropical seas. THE ASSERTIONS:
they will find all they need in the aquarium. because of their aggressive nature. various damselfishes. mals” at all. grow. Please allow me to deal with these misconceptions, one by one. SHORT RATIONS?
Should we really be underfeeding our fishes? No, not under any circumstances. Coral fishes are inhabitants of tropical seas with a more or less constantly high temperature (78-86°F or 26–30°C) and hence have a metabolic rate similar to that of warm-blooded animals. On the reef they normally have a wide spectrum of foods available, and they swim in a permanent plankton “soup.” In addition to the periodic influence of the monsoon, the limiting factor is higher-rank predators that prevent them from feeding without pause; access to food is regulated by the interplay of caution and hunger. Allowance can be made for this in the aquarium by feeding small portions as often as possible (using an automatic feeder). The concept of “short rations” (intentionally feeding less than recommended) conflicts with the natural behavior of coral fishes, especially because the majority (for example herbivores and planktivores) need to feed continuously. Hungry fishes invariably exhibit behavioral disturbances: they may constantly hide in order to save energy, or exhibit atypical aggressive behavior because they must continually do battle with competitors for food (a situation that doesn’t exist on the reef because so much food is available). It is quite simply cruel to make fishes go hungry in the interests of maintaining
water quality. Nowadays there is plenty of state-of-theart equipment to handle wastes. Fishes, as poikilothermic (cold-blooded) organisms, can survive relatively long periods of want before they die of starvation. This can create the impression that they don’t need much food, but that is not true—they merely die much more slowly than warm-blooded creatures. SELF�SUFFICIENCY?
It is certainly common to read the argument that sufficient plankton production will take place in a “functioning” reef aquarium. But the only such production that regularly takes place involves the larval stages of various bristleworms (readily visible at night), flatworms, coral larvae, and, in the case of crustaceans, planktonic shrimps or a couple of amphipod species, some edible and some not. Such a diet will not satisfy even the most basic requirements of any fish. At best, it provides emergency rations to stave off immediate starvation. I venture to assert that without supplementary feeding, even in a mega-aquarium, not even a pair of anthias would get enough to eat in the long term, and they too would starve. I regard as completely absurd the claims of one hobbyist who “feeds” his numerous (22) relatively large fishes only on the spawns of two pairs of cleaner shrimps. Given that the four Lysmata specimens, being hermaphrodites, release their larvae every 11 days, and at night when the fishes are sleeping, it is not very difficult to imagine how hard the latter will find it to get by. A further, particularly spicy gem is one author’s opinion that not feeding the fishes is a very important factor in the maintenance of a reef aquarium, though of course initially this may seem somewhat risky. I hope you will forgive me for not citing the sources of these and similar claims here, though I will be happy to provide the
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I
think observing the same �sh for years
is a tremendously rewarding experience.
appalling boredom. The monotonous life that afflicts fishes in an aquarium completely overgrown with corals, which vastly reduces the swimming area available to them, will result in every possible type of stereotyped behavior, such as circling, swimming up and down the glass, etc. GROUPS OF DAMSELS?
information to anyone who is interested. I have plenty of them to choose from, and anyone who follows the discussion on aquarium-hobby forums on the Internet for any time can easily obtain the same sort of “information” for himself. SINGLES?
Among all the thousands of coral-fish species known to us, there are only a very few that are truly solitary, and the further our knowledge of their biology increases, the smaller the number becomes. Almost all live in pairs, in family groups, or in schools of variable size, which in turn exhibit variable social structures. This is a topic that I have been discussing with growing vehemence for some 20 years, and I will outline it only briefly here: dear aquarists, you can keep any fish in pairs, and even in groups if you have a suitably sized aquarium and knowledge of the biology of the species in question. The majority of coral fishes are hermaphroditic in one way or another, so the laborious selection of a male and female is unnecessary; we need only to pick two fishes of different sizes. They will then sort it out for themselves. But keeping fish in pairs will work only if you feed sensibly (and not just in terms of quantity but also of quality) and if the food accords with the requirements of the species in question. A fish should not just be fed with any old type of flake or pellets (even if packed full of appetite stimulants and taste enhancers, colorants, vitamins, hormone substitutes, and all manner of unsaturated fatty acids) but should be able to recognize its food, by its form, as something it would eat in the wild, or because it resembles the prey animals that accord with its natural hunting behavior and encourage an appropriate response. Dried foods can be given in addition, but a wide variety of top-quality frozen food is almost indispensable. Our fishes are wild animals, and as such are endowed with a highly evolved behavioral repertoire, in particular as regards their feeding strategies. On the reef this behavior accounts for up to 80 percent of their daily activities. (Juveniles are always more aggressive than older fishes: they need to grow, require more food, and hence are also more active.) If we reduce this to a mere 10 percent (or to zero), then it is not fishes that we have in the aquarium, but behaviorally distorted creatures that attack one another when hungry or live a life of
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The misinformation on this point would be reason for a good laugh, were it not so tragic. We read and hear everywhere that members of the Pomacentridae—that is, a wide variety of yellow-tailed or yellowfinned damselfishes, all Dascyllus species, and many others of these belligerent, predominantly blue jewels— should be kept in groups to dilute aggression. The impression that one gains through superficial observation on the reef is deceptive, applying mainly to differently colored juvenile stages. Even where numerous individuals congregate in a particularly favorable area of habitat, we are actually seeing pairs that spend the entire day defending a specific small territory. Aquarists who decide to take the “group maintenance” path with these fishes apparently have a bit of a taste for gladiatorial combat! These fishes will fight until only one pair is left, or even a single fish, specifically when the level of aggression has been raised to such new heights by the endless battles that the fishes must first remember the need for a partner, even before any pairing has taken place. The gleaming blue mass displays in the dealer’s tanks give no hint of the fact that the largely deceptive peace results from the absence of anything on which to base terr itories. If a large block of rock or coral was placed in such a tank, the picture would change at a stroke. Thus, with a few exceptions (some Chromis species, Amphiprion spp., Abudefduf spp., Paraglyphidodon and Neoglyphidodon spp.), pomacentrids should be kept only in pairs. If they are well fed they will all exhibit interesting courtship and spawning behavior, and aggression towards other aquarium occupants will be contained within tolerable bounds (Thaler 1998). Innumerable species of pomacentrids adorn practically every intact underwater landscape, and hence pairs of these fishes should be included in the population of any reef aquarium. To my mind, there are no better fishes, as long as they aren’t starving. And it is perhaps worth mentioning, as an afterthought, that the same applies to all torpedo gobies (dartfishes) and all their relatives. Moreover these are found exclusively in pairs on the reef as well. SHORT�LIVED?
It is only in some reef aquaria t hat coral fishes don’t live a long life, and in the wild they can be “as old as the hills,” as has been demonstrated by many a chance observation. There are a very few families of small gobies
I
t is cruel to stuff tiny juveniles of large �sh species into small tanks.
gelfishes) have a metabolic rate corresponding to their eventual size, as they have more body mass to build and for that they must eat more than small surgeonfishes and dwarf angels. Because of this they are more aggressive and violent in their competition for food, and right from the start they are troublemakers because their requirements aren’t being met. Once again a basic example to make the point clear: a pair of Yellow or Brown Tangs ( Zebrasoma flavescens or Z. scopas) will do very nicely in a 150-gallon (600-liter) tank. These species attain an eventual size of around 10 inches (25 cm). By contrast, the Sailfin Tang ( Zebrasoma veliferum), which can attain an eventual size of up to 24 inches (60 cm) on the reef, will very soon become an aggressive bully and constantly disturb the peace. FISHES VERSUS HARMFUL ORGANISMS?
This can be summed up immediately: it doesn’t work in the long term. Even the most efficient glass-anemoneeating Chelmon will begin to waste away if it isn’t given adequate supplementary food after it clears away the Aiptasia. All the purported turbellarian-eating wrasses will indeed take these flatworms now and then, as will some lyrefishes and puffers, but they do not always have a lasting effect on these unwanted pests, and will
Salarias fasciatus
will starve to death when the algae that they eat runs out.
themselves suffer from lack of food unless their diet is supplemented. Fishes that initially eat something that we regard as a nuisance, for example turbellarians, soon abandon the practice because the “feedback” from the poisonous worms eventually sets in and lets the fish know that it is eating an unhealthy diet. Underfeeding will make the situation worse; the best “workers” are fishes that are fed a varied diet of good quality. They will regard turbellarians and (very occasionally) shell-less gastropods, glass anemones, and dwarf anemones as interesting supplements to their diet. Phalaena gobies may dig away a red coating of cyanobacteria, but they don’t eat it—they are after the microorganisms living beneath it. If the aquarium environment does not improve, the “slime algae” simply form again in different places. Algae-eating blennies such as Salarias fasciatus will die when the microalgae they can metabolize have all gone, as they cannot get by on thread algae alone; the same also applies, only less dramatically, to various algae-eating surgeonfishes. Bristletooth surgeonfishes (for example, Ctenochaetus spp.), which assiduously scrape away at an algaecovered rock, are in fact eating the bacterial coating on the algae; the algae are pulled away incidentally. No fish can check a pre-existing, stubborn over-proliferation of any particular organism. It may, however, be true that its presence adds more variety to the aquarium, and has an overall favorable influence on the environment, at least as long as all goes well for the fish itself. Exponential proliferation of any particular opportunistic organism occurs as the result of a poorly balanced aquarium environment, and fishes are not suitable countermeasures for dealing with such acute problems. At best they may nibble away at the symptoms, but what is really needed is prevention. A N D F I N A L L Y, A F I S H I S J U S T A F I S H ?
When looking at one reef aquarium or another, I sometimes get the impression that in the owner’s eyes all fishes are the same—especially when no attention has been paid to the requirements of the varied community of fishes. They all swim around in an anonymous throng, taking little notice of one another except to show aggression, and in fact trying to avoid one another. To the untrained eye, they are all just “fish” to be treated equally. After all, we apply this philosophy to our own children—why not to fishes as well? This standardized approach is all the more painful given the fact t hat it is
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among the fishes that we find the greatest diversity of life forms within the Class Vertebrata. Among closely related species (and even within the same species where it occurs in a variety of habitats) there are sometimes major differences, and this applies not only to appearance but in particular to behavior. The
A well fed trigger�sh will not eat cleaner shrimps!
differences between different genera and different families are unimaginably large, and much is still completely unknown. Take wrasses, for example, which exhibit an immense, almost unimaginable repertoire of adaptations to their individual habitats: they may be bottomoriented or live in mid-water, among corals or algae, in coral rubble or on sand flats, and every single species has a particular social behavior and different requirements as regards habitat structure, food, etc. Or gobies, which live on the sand or in it, as free-swimmers in the case of the dartfishes, or in symbiosis with pistol shrimps. The anemonefishes are often host-specific, with different species selecting different symbiotic anemones. One can barely imagine the variety of the almost infinite numbers of damselfish species that exist, likewise in the case of angels and butterflyfishes—there are so many, and their modes of behavior are so different. Often we can only guess when it comes to the refined specializations that we see in triggerfishes, pipefishes, and their relatives, as our knowledge is limited. The stealth and ambush predators, such as moray eels and frogfishes, are fascinating animals to feed, but require special care in stocking as they can ingest smaller fishes and produce large amounts of nitrogenous waste. Even in a small reef aquarium it is possible to fulfill the fundamental requirements of the resident fishes properly. Make sure these requirements are not entirely subordinated to human aesthetic desires: from the fishes’ viewpoint, one stony coral is pretty much like anoth-
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er, either edible or unpleasant, useful for shelter or not. They aren’t at all interested in how attractive it is. Some fishes do poorly under brilliant lighting that mimics a shallow-water reef. Decorative caves must have at least two entrances; tightly stacked live rock backgrounds are of little use to the fishes as they cannot swim through them. Room-divider aquaria should contain a large number of different-sized caves that cannot be seen into, as otherwise stress is inevitable in the long term. Algae-coated corners in the aquarium, deep substrate with the widest possible variation in grain size and interspersed with fragments of coral, even a bit of detritus in corners with little current— all these will make it easier for the fishes to settle in and ultimately feel at home. Of course, sufficient food to suit every taste should be available. When given the opportunity and the correct conditions, different fish species will indeed behave differently. And then even the aquarist who has no prior biological training, whose interest is only in having something bright and colorful to look at, will suddenly discover completely new aspects of his fishes: wrasses, for example, no longer circle madly around and across the aquarium, but drift around watching a goby digging in the sand. Surgeonfishes go to work on previously uninteresting bits of reef and no longer perform stereotypical patrols. Damselfishes begin to clean a spawning cave, symbiotic gobies rest happily near their own tunnels, and even the pistol shrimps appear at ease. And all at once there exists a very special kind of harmony that really does communicate itself to the observer—not just because of the blue, red, or yellow fishes, but also precisely because one fish isn’t the same as another. REFERENCES
De Graaf, F. 1977: Tropische Zier�sche im Meeresaquarium. Neumann-Verlag, Melsungen, Germany. Delbeek, J. C. and J. Sprung.1996. Das Riffaquarium, Vol. 1. Dähne-Verlag, Ettlingen, Germany. Engelmann, W. E. 2005. Zootierhaltung Fische—Tiere in menschlicher Obhut . Harri-Deutsch-Verlag, Frankfurt, Germany. Fosså, S. A. and A. J. Nilsen. 1993. Das Korallenriff-Aquarium, Vol. 3. Schmettkamp-Verlag, Bornheim, Germany. Gibson, R. N. 1996. Life in a �uctuating environment. In: Pitcher, T. J. (Ed.): Behaviour of Teleost Fishes, Elsevier Science Ltd., St. Louis, MO. Klausewitz, W. 1989. Über Schmerzemp�nden und Leidensfähigkeit bei Fischen. Zeitschrift für Fischökologie 18:65–90. Thaler, E. 1995. Fische beobachten—Verhaltensstudien an Meeres�schen und Wirbellosen im Aquarium und im Freiwasser .
Ulmer-Verlag, Stuttgart, Germany. Thaler, E. 1997. Fischpolemik. DATZ 50(3):164–172. Thaler, E. 1998. Riffbarsche ins Riff-Aquarium! DATZ 51(8): 524–529.
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aquarium portrait |
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RENÉ VACHOVEC
highs and lows Successes and hard lessons learned over a dozen years of building an outstanding reef dominated by stony corals and giant clams
E
ven as a small child, I was fascinated by the underwater world in my parents’ freshwater aquaria, where there was always something interesting to see—I never complained about being bored. It wasn’t long before I had my very own aquarium, which I lovingly maintained and of which I was very proud. Over the years, my aquarium got bigger and my equipment more sophisticated, and the growth of my aquatic plants was almost explosive. I spent many happy hours and a lot of effort on this eye-catcher in the living roo m. MY DREAM OF A MARINE AQUARIUM
I first encountered a marine aquarium in the store of my aquarium dealer in Chemnitz, Germany. It was, quite simply, fabulous: vibrant with color and populated by numerous exotic corals, fishes, and other strange and
C E V O H C A V É N E R : S O T O H P L L A
wonderful livestock I had never before seen. I could hardly tear myself away. I purchased the relevant literature and persuaded my wife that we really must have a marine a quarium. Without further ado, I ordered a 500-liter, 150 x 60 x 60 cm (132-gallon, 60 x 24 x 24 inch) Panorama aquarium and reinforced the floor of the room with steel girders to avoid future worries about t he load. A welded steel frame with an outer wooden cabinet served as the base and a compartment for filtration equipment. Rather naively, I started out with the minimum amount of equipment: two 150-watt HQI lamps, some blue fluorescent lights, a simple induction pump and trickle filter, the standard for marine systems at that time, a small reverse osmosis unit to prepare water for topping up, and a few powerheads to create current. It was state of the art, I thought.
As on the coral reef in the wild, the corals grow packed closely together and compete for empty space to colonize. Without regular “gardening” to thin them out, reciprocal stinging would rapidly develop among the corals.
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Left: A huge Tridacna derasa during spawning. Below: The same aquarium—water is heavily clouded by the oocytes from 20 giant clams, and the protein skimmer is having difficulty maintaining clear conditions.
further increased the population of the aquarium. As soon as the water parameters permitted, I added my first stony corals. At first I thought the aquarium would never be “full,” but I would prove to be wrong. PROBLEMS AND SOLUTIONS
SUCCESS!
With the addition of freshly made-up salt water and 110 kg (242 lbs.) of living rock, the project became a reality. The maturation phase went just as the books said it should. I was immensely pleased at the daily incremental progress. The first fish I acquired was a Zebrasoma flavescens, which, 12 years later, still enjoys the best of health today and is the “boss” among my four surgeonfishes. Thereafter, whenever my wallet could stand it, I
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With the introduction of additional fishes and the heavier feeding that required—after all, nobody must go hungry—I experienced the first problems with my aquarium concept. The trickle filter did its work and oxidized nitrogenous compounds to nitrate, which is the purpose of this type of filter. But the constantly increasing concentration of nitrate couldn’t be countered, even with regular partial water changes. I was disappointed that the living rock didn’t solve the problem as some of the literature suggested it would. And then algae began to proliferate and the stony corals exhibited increasing signs that they were unhappy. So I learned my lesson the hard way, and concluded that the trickle filter wasn’t the right one for my purposes. I replaced it with a homemade protein skimmer augmented with a nitrate filter to combat poor water quality. The water parameters now rapidly attained an ideal level. But the resulting immense coral growth brought new problems in its turn: my next lesson was that carbonate hardness and calcium content do not remain in the optimal zone by themselves—so I constructed devices to monitor and add calcium carbonate myself, which meant I could adapt them precisely to the dimensions of the tank. The lighting was also adjusted to provide better conditions for growth (see equipment summary). My next acquisition was a cooling system to keep the water temperature in the penthouse apartment at a tolerable level for the corals, even in summer. HIGHS…
After these changes in the equipment, things finally started to go right. It wasn’t long before the aquarium was densely packed with Acropora corals—a truly fan-
AQUARIUM Details SIZE, VOLUME, YEARS ESTABLISHED: 150
x 60 x 60 cm, silicone-sealant construction, Panorama model, 600 liters total volume (with sump), established for 12 years. CORALS AND OTHER SESSILE INVERTEBRATES: Various stony corals, including Trachyphyllia, Fungia, Euphyllia, Pocillopora, Acropora, Porites, Stylophora, Montipora, Seriatopora, Montastrea, Hydnophora, Platygyra; plus 20 Tridacna clams, encrusting anemones, sponges, 110 kg of living rock. NON�SESSILE INVERTEBRATES: Various hermit crabs, shrimps, brittle stars, gastropods, worms, etc. FISHES: Acanthurus leucosternon, Zebrasoma xanthurum , Zebrasoma flavescens, Ctenochaetus strigosus, Cirrhitichthys falco, Gramma loreto, Pterosynchiropus splendidus, various Pomacentrids. LIGHTING: Two 250-watt HQI Megachrome Corals (dimmable), four 54-watt T5s (one Pure Actinic, one Daylight, two Blue), four 35-watt Halogens (dimmable to zero), one 3-watt Moonlight precisely mirroring the lunar cycle (switched with a homemade controller). WATER MOVEMENT: Deltec HLP 8070 (circulatory pump), four Tunze Streams with multi-controller (current). WATER MANAGEMENT: Protein skimmer (homemade), Deltec nitrate filter (two-stage with vodka as nutrient solution), phosphate filter (homemade from a redundant reverse osmosis unit), UV-C compact irradiator for sterilization (9-watt), ozonizer (installed but not yet used), calcium-carbonate monitor (homemade from a Sander protein skimmer), lime-water doser (homemade), automatic top-up device consisting of a reverse-osmosis unit with purification filter and 30liter reserve tank, cooling via a Titan 1500, two-stage blower with independent control for emergency cooling (homemade). CONTROL: IKS Aqua Computer for temperature, conductivity, lighting, etc., as well as two pHs (AQ + calcium carbonate monitor), two Redoxes (AQ + nitrate filter). SAFETY: IKS SMS Controller with water-leak sensors with wiring (homemade). WATER ADDITIVES: JBL trace elements. PARTIAL WATER CHA NGES: Every 14 days with Tropic Marin sea salt, plus Bio-Calcium and Bio-Magnesium from Tropic Marin when required. OWNER: René Vachovec, Chemnitz, Germany. A large percentage of the equipment used was made by René Vachovec himself. As a result all the devices are custom-built and the limited space in the under-tank cabinet can be used optimally. Nothing is left to chance: the aquarium equipment is monitored by an aquarium computer with a specially-designed safety system (IKS SMS Controller).
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After his populations of small �shes and shrimps mysteriously dwindled, the author designed this trap to catch the culprit, a Debelius’ Reef Lobster.
tastic sight. I was now able to give one coral or another to aquarist friends or swap them for different species. At this time there was even a mass spawning of Tridacna clams, with the larger individuals expelling oocytes, an interesting spectacle that seriously tested the protein skimmer but above all demonstrated how well the aquarium inhabitants were feeling. Visitors eagerly pressed their faces to the front glass of our aquarium. Obviously, the preparation and maintenance work on the aquarium had long since exceeded the time and trouble I had expended on my freshwater aquarium, but the results were worth it. The unique feature of a marine aquarium is that it changes continuously, so there is always something new to see. …AND LOWS
For a long time, my aquarium ran at a high level of equilibrium. Then a defective electronic conductivity meter used to measure salinity destroyed practically everything. It had gone wrong three years previously, and because of the expense I hadn’t replaced it immediately but instead relied on a simple hydrometer. After a few months some of the corals began to suffer. Anyone who knows his aquarium will immediately notice the smallest changes in the polyp landscape. But that was of little use to me, as the reason for the problem remained a mystery. Numerous corals died, and I was frustrated by this unpleasant turn of events. I performed and evaluated a huge variety of water tests, as advised, but in vain. It was only by chance that I found the solution when I introduced new corals into the aquarium and noticed the striking blurring effect that occurs when waters of different salinities are mixed. At first I assumed that the water from the tank where I had purchased the corals was of unsuitable salinity, but then I learned that the density of my own aquarium water was far too high! My problem was purely and simply the r esult of a defective hydrometer. It was an embarrassing mistake for me. RENEWED SUCCESS
To my great delight, after the salinity had been slowly brought back to normal the aquarium recovered very quickly, and over the next two years things continued to get better. Success was once again mine; that is true to this day. The aquarium is once again densely packed
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with corals that are thriving to such an extent that regular “gardening” is required to prevent them from stinging or overshadowing each other. In addition to maintaining corals I have developed a liking for giant clams. Because they are more difficult to acclimate to aquarium conditions than corals, I have placed the clams in the most favorable spots in the aquarium. A TROUBLEMAKER
Unfortunately, in the course of time my fish and shrimp populations have been decimated to some degree. Around six years ago—with no idea at all of the potential consequences—I acquired a dainty little Debelius’ Reef Lobster (Enoplometopus debelius), although it seemed to disappear after its introduction. Initially, I still found the remains of its molted shell from time to time, but later I didn’t even see that and so assumed that the creature was no more. About three months ago I found it again while investigating the reason for the nocturnal disappearance of my other livestock. I managed to capture the now 10-cm-long lobster with a special trap (once again, homemade). These fascinating creatures may be well suited to a species aquarium or as tankmates for large fishes, but I would strongly advise against keeping them in the reef aquarium with small fishes and crustaceans. SUMMARY
Over the years I have experienced both highs and lows with my marine aquarium, but my fascination with and passion for this demanding hobby remain as great as they were on the very first day. In conclusion I would like to advise all novices not to be downhearted at their failures and setbacks, but to determine the causes of their mistakes and eliminate them. It will be worthwhile!
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F
or many years, rather specific habits of illuminating coral reef displays have been firmly entrenched in the reef aquarium hobby. What began as well-intended guidelines for recommended wattages and types of lamps has turned into misguided lighting advice from nearly every corner of the hobby. The misinformation is largely promulgated by aquarists who simply pass along the unchallenged—albeit errant—advice that they’ve read or been given. In short, in the application of light, the hobby has strayed toward less useful lamp spectrums and the use of excessive amounts of light. The very first mistake that most aquarists make is to seek information about the type of lighting they need based on the size of their aquariums, rather t han on the needs of their animals. This error is epidemic in both scope and tragedy, since the majority of reef aquarists do not assemble a specific list of compatible corals and reef creatures before reckoning lighting needs. To me, the transgression is frankly staggering. The needs of the livestock must come first. Only after the corals’ specific requirements are determined can the tank size be considered in decisions about lamp style, reflector type, and total wattage. Beginning with a list of compatible reef species with similar lighting needs is the only way to set up a reef display responsibly. Creatures from a specific part of the reef will fare better in a
a new perspective on
reef lighting by Anthony Calfo
R E L A H T . E : S O T O H P
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biotope grouping than they will with a “garden reef” or random hodgepodge of corals (species from different biotopes, different reefs, or even different seas). For example, low-flow, deepwater, colorful Montipora species will never fare well in the same aquarium with shallow-water, colorful Acropora species, despite the fact that both of these lovely stony corals are generally called SPS corals—these two popular genera simply have dramatically different husbandry needs. One cannot standardize lighting (and water flow) for such disparate specimens, which are collected from reef depths that may differ by as much as 66 feet (20 m). This is the problem that so many aquarists run into after making the mistake of choosing lighting that fits the tank size. For long-term success, it’s crucial to first select corals that will be compatible under the narrow parameters of space, water flow, feeding, and light in a home aquarium. The next, and perhaps simplest, aspect of lighting to ponder is the amount of power, or wattage. The tendency through the years has been to assume that more is better. Surpising as it may sound, this is not true, and in fact it can be harmful to apply too much light. Corals do need to reach a compensation point each day whereby they get enough nutrition to meet fundamental needs, such as respiration. But beyond the saturation point , no amount of excess light will improve zooxanthellate symbiosis. On the contrary, corals given excess illumination may suffer from photoinhibition (observed as pale or white specimens that have expelled some or all of their zooxanthellae). SPS coral enthusiasts often keep their corals on the edge of this precipice—where excess light causes them to become pale or pastel—and nefariously market them as “rare” specimens. I also find it disappointing, when reading message-board posts or chatting with fellow hobbyists abroad, to see 400- and 1000-watt lamps commonly recommended for particularly small aquaria (< 25 gallon/100 liter). These are usually examples of the aforementioned well-intended hobbyists giving new hobbyists advice on lighting without ever reckoning the coral species’ needs. But, with energy prices rising and economic issues becoming a greater concern, some reef keepers are now re-examining their lighting schemes and considering proper lowerwattage alternatives. Rules of thumb are not especially useful in reef lighting discussions.
R E L A H T . E : S O T O H P
Sadly, the deeper-water, lower-�ow corals such as Montipora species get lumped into the generic category of SPS corals and must suffer higher water �ow and higher lighting (intensity and spectrum) than is natural. Such corals are collected at greater depth and fare better in aquaria with more blueweighted spectrums of light, such as 14,000 or 20,000K lamps. Inset: It is a mistake to presume that all Acropora are high-light species. These lovely corals come from a wide range of depths on the reef. Choose your lamps carefully!
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Common household egg crate, found at your local hardware store, is superb for focusing light into an aquarium. It has tapered grid sides—one to focus light downward and the other side to spread it. Notice the difference over your aquarium.
Nonetheless, I will offer one here and then qualify it a bit. For a typical “garden reef” (mixed species) home aquarium, 5–10 watts per gallon of reef quality lighting are required for a healthy coral display. Thus, a 100-gallon aquarium will generally require 500–1,000 watts of light. There are presumptions with this rule of thumb, however, including the following: bon (daily) (every 6–10 months) Diversions from this recommendation may allow higher wattage lamps mounted higher than usual above a reef display. This is a common example of what users of 400and 1,000-watt halide lamps must do to prevent burning or shocking corals. In this way, the intensity can be tempered and a greater spread of light is gained. But, unless the reef display is wide enough to utilize the broader spread of light, energy is wasted as some light falls out wattage lamp mounted closer to the water, with a stilladequate spread of light from a good reflector, would be much more efficient. To be even more energy efficient, let us also look at
the number of lamps typically used, and the ongoing expense of running a lighting system. For example, a traditional 6 ft./~2 m long aquarium would normally have four 250-watt (or 400-watt) lamps above it. But if we r un a moving light track (“Light Rail”) over the system, two 400-watt metal halide lamps will illuminate the display just as well, or better! Fewer watts of light are used, fewer bulbs need to be replaced, and the moving light source provides corals with a far more natural type of light, akin to the sun, coming from radiating angles. It’s a small wonder to me that more aquarists have not incorporated the moving light source into their systems. The energy saving is tremendous and coral growth is superb. exceedingly blue-weighted spectrums. The preference of aquarists, categorically, has been for bluer and bluer lighting. But this is not always beneficial for coral health and growth. On the contrary, a very blue-weighted spectrum is quite narrow in application for typical reef aquarium corals—broader spectrum lamps with more daylight and tions about lighting needs when considering the niches on the reef where given corals hail from. For example, a warm daylight spectrum (say, 6,500– 10,000 K) of light is suitable for Pom Pom Coral ( Xenia umbellata), which commonly occurs in ankle-deep water. Other popular animals from the shallows include many colorful Acropora, Porites cylindrica, and Entacmaea quadricolor opposite end of the spectrum are the deeper water corals favoring the blueweighted lamps (ala 20,000 K), such as the family Euphyllidae (Hammer, Octopus, Torch, and Elegant Corals), red Open Brain Corals ( Trachyphyllia), many of the Montipora species, and quite a few large-polyped solitary corals such as Fungia, Scolymia, and Cynarina. http://www.H2OLifeFoods.com The reality, though, is that most INNOVATIVE PRODUCTS FOR MARINE FISHES & CORALS: MYSIS SHRIMP, KRILL PACIFICA, aquarists do not know how to make a ROTIFERS, CYCLOPS, CORAL FOOD, SPIRULINA/BRINE SHRIMP/MYSIS, CLAMS ON THE HALF-SHELL, SILVERSIDES IQF, FRESH KRILL, DRIED SEAWEEDS, SPECIALTY ADDITIVES, AND MUCH MORE. proper biotope exhibit—so they comPhone 619.434.3333 Fax: 619.434.2711 promise on lighting, using a blend or
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O F L A C Y N O H T N A : S O T O H P
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Moving light tracks save electricity and lamp replacement costs—while delivering more natural light from radiating angles via the moving lamp(s). Too often, corals are exposed to excess wattage or intensities and blue-weighted spectrums. Determine where your corals hail from on the reef to reckon the optimal light for your display.
balance of light to get optimal and appropriate growth and color for a gamut of coral species in a mixed garden display. For single-lamp or single-bulb-type applications, a 14,000 K lamp is likely the best solution. For multilamp combinations, a blend of lamp colors can yield optimal results. It will, again, depend on the corals kept and their specific needs. Each tank, however, invariably favors one type or category of corals over others. Thus, if your system has a hearty sampling of Acropora frags and small-polyped Zoanthus, you will want to lean towards warmer lighting: a 10,000 K lamp or two, supplemented by flanking 14 K or 20 K bulbs, would likely be pleasing. allimorphs, large-polyped zoanthids, and/or Montipora would do better with a quality 20,000 K lamp supple is no easy answer for lighting coral reef displays—it is all a matter of finesse. But do heed the warnings and experience of practiced reefkeepers and coral farmers. Good planning will insure many years of pleasure and success with growing your personal reef garden.
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O F L A C Y N O H T N A
species spotlight |
ROBERT M. FENNER
Two color morphs of Entacmaea quadricolor : the so-called Rose Anemone, rear, and the more common greenish Bubble Tip at the front in a display aquarium at Interzoo 2008.
the
Bubble Tip Anemone a hardy species for all clownfishes Entacmaea quadricolor (Ruppell & Leuckart, 1828)
R E N N E F . M T R E B O R
TAXONOMY: Phylum Cnidaria, Hatschek 1888 —anemones, corals, and jellyfish Class: Anthozoa Subclass: Hexacorallia Order: Actinaria Suborder: Nyantheae, Carlgren 1899 Tribe: Thenaria, Carlgren 1899 Subtribe: Endomyaria, Stephenson 1921 Family: Actiniidae, Rafinesque 1815 Genus: Entacmaea, Ehrenberg 1834
OTHER SCIENTIFIC NAMES and nudum nomen*: Cymbactis actinostoloides Entacmea quadricolor Entamacea quadricolor Gyrostoma adherens (Ehrenberg, 1834) Gyrostoma haddoni Lager, 1911 Gyrostoma heliant(h)us Gyrostoma hertwigi Kwietniewski, 1897 Gyrostoma quadricolor (Leuckart & Rüppel, 1828) Physobrachia douglasi Physobrachia ramsayi Radianthus gelam
* Nomen nudem is Latin for “naked name,” something that appears to be a scientific name but lacks the recognition that comes from publication of a full description of the species. A nudem nomen can become the established name of a species upon formal publication. COMMON NAM ES: Bubble Tip Anemone, Rose Anemone, Bulb Tip Anemone, Four-Colored Anemone, Maroon Anemone, BTA.
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Pair of Maroon Clown�sh or Spinecheek Anemone�sh (Premnas biaculeatus) with their large green Bubble Tip Anemone in the wild Right top: Color variant with distinct striping and purple tips Right: Extremely unusual pink morph photographed by the author in Palau Redang, Malaysia in the 1990s
D I S T R I B U T I O N : Found
K T
. R E N N E F . M T R E B O R , H P R O M K N I P ; L E A H C I M . W T T O C S , P I T E L B B U B D E P I R T S D N A E G A M I E G R A L
in the Red Sea, along Africa’s East coast, throughout the Indian Ocean to the Western Pacific; Australia to most of Japan, out to Micronesia and Melanesia. D E S C R I P T I O N : Have long tentacles (up to 4 inches), typically with an expansion (bulb) at the end. Columns, usually brown, reddish, or greenish, lack verrucae. Small pedal disc, typically buried in amongst rock with only tentacles showing. The smooth column and bulbous tentacles are definitive for this clownfish-symbiotic species. HABITAT: Found on reef tops in shallow water to deeper water on reef slopes. May be solitary or live in a field of cloned individuals. B E H A V I O R S : Bulbs at ends of tentacles can be enlarged or rounded for reasons unknown. These bulbs are usually lacking in specimens that have no symbiotic anemonefish. If touched, the tentacles can collapse, change color to grey-green. This is the most common host actinarian in the wild, serving 13 species of anemonefishes (and with training, all clownfishes in captivity). D I E T : Should be fed once or twice weekly with small pieces of cut-up meaty seafood items, offered via a feeding stick to place scallop, fish flesh, shrimp, or whole
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Vivid red morph. Bubble Tips with clown�sh often do not display swollen tentacle tips.
small fish (e.g. silverside) directly against the tentacles. Some writers suggest that this species can subsist on simple photosynthesis alone. This is not the case. If your specimen appears to be shrinking or losing vitality, immediately start improving its nutrition by direct feeding. Remove uneaten foods. If your anemone has no feeding response, try another day. Care should be taken to remove egested wastes; these are encapsulated masses that are ejected a day or two after feeding. A Q U A R I U M C A R E : Among the large symbiotic sea anemones that serve as hosts for clownfishes, Entacmaea quadricolor is the easiest to care for, particularly aquarium-cloned specimens. Provide reef-aquarium water quality conditions of stable, near-seawater-strength specific gravity (1.025), an absence of ammonia, zero nitrite, reasonable nitrates (under 5 ppm), very low phosphate (under 0.2 ppm), suitable calcium (300-400 ppm), about three times this in magnesium, and dKH 8–12. Lighting can be moderate. Fluorescent bulbs will suffice, but illumination should be boosted if the water is deeper. Metal halide or intense LED lighting is advised for water over 24” in depth. A good-sized Bubble Tip, which may be a foot across in the wild (I have seen them up to 20 inches [50 cm] in diameter), will need a spacious, well-established setting, with rock suitable for attachment. If conditions are not to its liking, you may find your Bubble Tip wandering about. (Do keep all pump intakes, overflows, and heaters covered or screened if keeping one or more anemones.) Current can be brisk, though it should not be directly aimed at the anemone itself. Aim for a tank volume turnover of 10 to 20 times per hour.
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Some care should be taken in selecting suitable tankmates. Large crustaceans (crabs, lobsters), the usual suspects (puffers, angels, triggerfishes) will likely chew on your anemone. There are many instances, too, of allelopathic incompatibility when this and other anemones are crowded too near other classes of cnidarians. Simply put, anemones and corals can kill each other if placed too close together. You can alleviate this interspecies chemical and physical aggression by careful placement and by using chemical filtrants such as activated carbon or ozone. Above all, select a healthy anemone and carefully acclimate and introduce it to your system. One reason for the popularity of E. quadricolor is its reproductive proclivity. A healthy specimen will often asexually give rise to new individuals by simple fission of the foot/pedicle or bilateral splitting through the body. Be ready to share the wealth by trading or selling your excess stock, unless you are interested in seeing how anemones can dominate an entire tank. Captive-produced animals are far more facile at adapting to new aquarium conditions, and choosing cultured specimens reduces collection pressures in the wild. REFERENCES
Fautin, D. G. Hexacorallians of the World . http://hercules.kgs.ku.edu/Hexacoral/Anemone2/ Fautin, D. G. and G. R. Allen. 1992. Anemone Fishes and Their Host Sea Anemones. Western Australian Museum, Perth. 160 pp. Fenner, R. Anemones in captive systems. http://wetwebmedia. com/marine/inverts/cnidaria/anthozoa/anemones.htm Wikipedia: Bubble Tip Anemone. http://en.wikipedia.org/wiki/Entacmaea_quadricolor
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m a r i n e - a q u a r i um b a s i c s f o r n e w c o m e r s —D A N I E L K N O P
What is
ozone?
Does a coral-reef aquarium need ozone? What exactly is ozone? Should the beginner go out and buy an ozonizer? Under what circumstances is it wise to acquire one, and what points should one always bear in mind when using ozone?
T
he same gas that most people know as the one that makes up the protective layer in the Earth’s atmosphere—or combines with nitric oxide to make up the harmful layer of smog over big cities—can be used in the aquarium hobby to purify water. While an oxygen molecule consists of two atoms (hence the chemical symbol O 2), the ozone molecule has three atoms (O3). At room temperature and under normal atmospheric pressure it is unstable, so the extra atom is rapidly given off and the ozone becomes molecular oxygen. But once free, the single oxygen atom is highly reactive and can combine with other substances, oxidizing them. This is the source of the huge oxidation power of ozone, and ultimately also the basis of the tissue-damaging and water-purifying effects of this gas. Ozone is 1.65 times as heavy as air, and hence sinks downwards in the atmosphere. It has a typical odor, detectable even at concentrations of 1:500,000, but as little 1/20 of that concentration is harmful to humans and can cause headaches and nausea. WHERE DOES OZONE COME FROM?
Ozone is formed from bivalent oxygen when the latter is exposed to either ultraviolet radiation (242 nm wavelength) or a specific electrical field. In the case of water purification, air is normally passed through an ozonizer containing a source of high voltage (at least 3 kilovolts) where a silent discharge takes place, during which part of the atmospheric oxygen is converted into ozone. However, humidity can significantly limit this process, so if the air in the roo m is damp it must be
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dehumidified before passing through the ozonizer (see opposite page). HOW DOES OZONE WORK IN THE AQUARIUM?
The oxygen atom set free by the breakdown of ozone is a powerful oxidizing agent and can a) kill bacteria and viruses; b) destroy many organic compounds; and c) in higher concentrations, damage the living tissue of animals and plants. While the properties listed under a) and b) can be used for water purification, that mentioned under c) is one of the factors limiting the use of ozone in the aquarium. The advantages of using ozone in the aquarium are that it removes germs from the water and destroys unwanted organic compounds—and in the process also eliminates the so-called “yellowing” of the aquarium water that noticeably increases over time. In addition, even a small amount of ozone can increase the efficiency of the protein skimmer, so that just a tiny concentration of skimmable substances will suffice to fi ll the cup. Moreover, ozonization increases the oxygen content of the aquarium water. Nitrite is rapidly oxidized and converted into less toxic nitrate; consequently, careful ozonization can be a sensible way to counter nitrite toxicity. The biotoxins that can accumulate in the water during the aquar ium maintenance of corals and other stinging creatures can also be reduced by ozonization, and ozone increases the oxidation (redox) potential of the water. Any ozone concentration in the aquarium water,
WHEN IS THE US E OF OZONE RECOMMENDED?
Left: An “ozone booster” for pre-drying the air, �lled with silica gel, with a color indicator to show when the gel is exhausted
Below: Ozonizing equipment for the aquarium
The germicidal effect of ozone is usually overestimated; the ozone concentrations necessary for the effective elimination of germs is virtually impossible to achieve using the equipment available to aquarists (Krause 1995). In cases of intensive fish maintenance, for example in the aquarium trade or where large fishes are maintained in public aquaria, the use of ozone may nevertheless be indispensable in order to avoid pollution peaks that cause a rise in nitrite concentration. However, even in such cases it should be used outside the tank and the aquarium water must itself remain ozone-free, as otherwise tissue damage in the animals is inevitable. The use of ozone is not absolutely necessary in the reef aquarium, as demonstrated by the numerous ozonefree reef tanks in successful operation (Knop 2008). The amounts of nitrite produced there are smaller because of the lower fish density, and are usually removed by bacterial activity in the living rock. But protein-skimming in the reef aquarium can be improved through the use of ozone. The introduction of ozone at the rate of 3–5 mg/hour directly into the protein skimmer will not, as a rule, have any negative effect on the aquarium biotope, but can improve the water’s condition and help to rid it of yellowing and dissolved toxins from corals. WHAT POINTS AR E IMPOR TANT
C I D E M A U Q A O T O F S K R E W : S O T O H P
even if insufficient to be harmful to living tissue, can have undesirable effects. The most significant of these is the characteristic ability of ozone, when present in a sufficiently high concentration, to transform minerals such as manganese or iron—important trace elements for plants (and thus also for the symbiotic algae in the corals)—to a water-insoluble state, so that they are no longer available to the organisms that require them. A further potential effect is the release of substances bound up in chemical complexes. This can be dangerous—for example, if organic iodine compounds (PVP-iodine, Povidone-iodine) are added to the marine aquarium to provide an iodine supply. Iodine is sometimes present in aquarium water in high concentrations, but is harmless by virtue of being bound to the PVP (polyvinylpyrrolidone) and not readily measurable by the aquarist. But ozone destroys such complexes, making the iodine immediately available and highly toxic: only a short time after the ozonizer is switched on, the water begins to smell noticeably of iodine and the invertebrates can be harmed. If ozone is present in the water of a reef aquarium, remember that it may be damaging to the invertebrates, in particular the corals, at lower concentrations than those harmful to fishes. For this reason ozone should always be used outside the aquarium, usually in the skimmer or ozone reactor, and any escape of residual ozone into the aquarium must be avoided at all costs.
WHEN USING OZONE?
prove protein-skimming efficiency, the water returning to the aquarium from the protein skimmer should be passed over activated carbon; if this takes place sufficiently slowly, the residual ozone will be eliminated. Make sure that the protein skimmer you use is of a suitable type; rotary skimmers, for example, are not (Brockmann 2008). avoid using any substances bound up in complexes (for example, trace element complexes)! first be passed through a dehumidifier (dehumidifying chamber with silica gel). room. If you want to be absolutely sure, detoxify the air vented from the protein skimmer using activated carbon designed for use in air, or pipe it outdoors. REFERENCES
Brockmann, D. 2008. Das Meerwasseraquarium—Von der Planung bis zur erfolgreichen P�ege . Natur und Tier-Verlag, Münster, Germany. Krause, H. J. 1995. Handbuch Aquarienwasser . Bede-Verlag, Ruhmannsfelden, Germany. Knop, D. 2008. Riffaquaristik für Einsteiger . Dähne-Verlag, Ettlingen, Germany.
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advanced aquatics |
Designing a
J. CHARLES DELBEEK
Dream System
when biology and architecture collide
O
ver the last 20 years I have been fortunate to visit private and public aquariums all over the world, and as an aquarium design consultant I have worked on projects for both private homes and public aquariums. This has allowed me to gain a very interesting perspective, not only on marine aquarium design and installation but also on the entire process of building/home design, tank design, and aquarium installation. This has been both a blessing and a curse: I have seen how little architects understand about aquarium systems and the needs of the animals that inhabit them and the people who maintain them. The first thing one must understand about architects is that, for many of them, it is all about the building;
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what the building will ultimately contain is of lesser importance. For them the task is designing a building that they want to build, or that the client wants to have built. On the opposite end of the scale you have the aquarium designer. For us it’s all about the animals and those who will maintain those animals. Of course aesthetics plays a role, but our primary goal is an exhibit that displays the animals well and allows them to thrive. We also want to design an exhibit, life support, and maintenance system that is easy to use and does not require that the operator be related to Houdini. The surest way to have a system that looks dirty all the time and in which the animals do poorly is to make it inaccessible and headache to work with. I cannot tell you how many
M O C . N G I S E D M U I R A U Q A D C J , K E E B L E D S E L R A H C . J
Left and at right: Pieter van Suijlekom’s magni�cent, expertly designed 1,532-gallon (5,800 L) reef aquarium, housed in his Open Fireplace Centre, in Vlaardingen, Netherlands. With connected seahorse tank, coral fragment tank, and sump, the system tops out at 2,074 gallons (7,850 L). Space for lights and access for cleaning are well thought out, with a front wall panel above the tank that retracts to allow comfortable maintenance. Wider than it is tall, the tank provides Pieter with excellent aquascaping opportunities.
times I have been contacted by architecture firms who want a tank installed (which they have already designed) that may look wonderful architecturally, but would be a disaster from biological and maintenance standpoints. For example, a recent project called for an aquarium that was 10 feet long, 5 feet tall, and 2 feet wide; at one end, the tank tapered down to a 10-inch width. At that height the acrylic would have to be at least 2.5 inches thick, so the actual tank space would be only 5 inches wide. On top of this, there was only 12 inches of clearance above the tank, leaving very little space for lights and access to clean the tank. Finally, nowhere on the schematic was there any space allotted to life support. In another case, a museum hired an architect to design several new exhibits for an aquarium expansion. The architect insisted on a concave front window for the reef tank. The problem with a concave window is that cleaning in the corners is very difficult; also, it prevents the placement of rockwork toward the front sides of the aquarium, so aquascaping is problematic. To top it off, the clearance above this 6-foot-deep tank was only 2 feet, making it impossible to get above the front window to clean it with a cleaning pole and pad. If you are fortunate enough to be able to build your own home or addition, and you would like to include an aquarium in the design, there are a few simple steps you should consider before you even hire an architect. First, decide what you wish to keep in the tank. This should be the main driving force behind the design of any aquarium. Once you have decided what type of exhibit you want, think about the size and shape. Thirdly, plan the life-support system and determine how much space you will need for it. A rough guideline is a 1:1 ratio of aquarium space to life-support system space. If you don’t know enough about aquarium system design, bring in someone who does. This person can then go about designing the system from top to bottom and work with the architect or builder to incorporate the aquarium into the overall design. Unfortunately, what I have just described is the exception and not the rule. In most cases the architect either decides an aquarium would be a nice design eleme nt to include, or gets a simple request from the client, such as “I want an aquarium that will wow the socks off my guests!” With very little to go on, the architect then designs an aquarium that fits in with the overall building
design. Again, an aquarium design specialist should be brought in, either by the client or by the architect, before this happens, not after the aquarium has already been designed. The architect should do what architects do best—design a building to reflect your vision—and the aquarium designer should be allowed to do what he or she does best: design a system that will work. Here are a few tips for potential aquarium owners and architects alike. ing, do not work well for an aquarium. This shape hampers maintenance, restricts aquascaping, and has an unfavorable surface area to volume ratio, which is not good for the inhabitants. height) to access the aquarium from above, especially if it is very high. cated either near the tank or in a separate space. cations. Consider fiberglass with an acrylic viewing panel: it’s lighter and can be cheaper.
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SOURCES|
the best local and destination marine retail stores
Vivid Aquariums
21126 Vanowen St. Canoga Park, CA 91303 San Fernando Valley (LA County) www.vividaquariums.com 800-993-0979
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Monterey County’s finest collection of marine specimens and supplies. We specialize in tank-raised and net-caught marine animals.
Aquarium Concepts
6920 Amador Plaza Road Dublin, CA 94568 Tel. 925-829-0583 www.aquariumconceptsinc.com
115 N. Milpitas Blvd. Milpitas, CA 95035 Tel. 408-262-3400 www.aquatic-gallery.com
With over 25,000 gallons of aquariums, we are one of the largest aquarium stores in the state. Unmatched selections of fish, corals, invertebrates, equipment.
Marine reef designer and specialist, the largest selection of corals and reef livestock in the Bay Area. Reefer’s Heaven! Tank design & maintenance.
E R O T S R U O Y T P U p a m s ’ r e d a e o n e ve r y
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f tic audience o as si u th n e t s o un tr y es t, m aches the larg b yis ts in the co b o h m u ri a COR AL re u ine aq d serious mar an rs e ep e fk e re d. -speak ing worl sh li g En e our to wn and y th in d s er d —an a re R AL g r facili t y to CO o re visi t ou ts tandin to s r to u g n yo i k te o o lo m ts s ro P bb yi to tra veling ho s a l el w as , n regio s. lo cal s tore iu ar m e xposure u q a c li b u p r o ness ra te o f $200 gi ves your busi e e m su ti is xr si e p al 0 su 5 eu Jus t $1 ne Sa ve 25 % o ff th e. ls e re e h AL Maga zi w R o n O C le b w la e n ai a v the x 60 banner on 8 6 4 ee fr a t e t. and g ar prin t con trac ye e n o a th i w websi te ser ve space. re to s re to s the �rs t 50 Good onl y for re: a y to learn mo d to ce n re w La 7 x 7 Con tac t James | 80 2- 985- 9 9 7 m o c t. s re fo ce@ree f 2rain CORAL ORAL james. la wren
1255 Johnson Ferry Road Marietta, GA 30068 Tel. 404-256-0070 www.marine�sh.net
350 Dorset Street So. Burlington, VT 05403 Tel. 802-860-1714 www.thepetadvantage.com
Our full-line aquarium store has everything you need to succeed with your marine environment. Healthy fish, corals, and more. Since 1998.
8870 Waltham Woods Rd. Parkville, MD 21234 Tel. 410-668-1200 Our full-line aquarium store has everything you need to succeed with your marine environment. Healthy fish, corals, and more. Since 1998.
Northern New England’s destination marine aquarium department with fishes, corals, invertebrates, and reefkeeping equipment and supplies.
C o m e i n a n d
11634 A Busy Street Richmond, VA 23236 Tel. 804-379-2466 www.�shworldric.com
PA S S O U T !
We pack every inch of our store with the most oddball and cherry-picked stuff, so it can be overwhelming! Full line of Tunze or Corlavue products in stock.
680 W. 92nd Street Bloomington, MN 55420 Tel. 952-838-0174 www.SWEmpire.com
90 Front St. South Issaquah, WA 98027 Tel. 425-392-5360
Simple beautiful marine aquariums, we show you how. Visit our site for more information.
Washington’s best selection of the highest quality aquatic livestock and dry goods. Specializing in saltwater fish,corals and invertebrates. Expert service and advice.
10 Ohio Street Terre Haute, IN (812) 232-9000 www.inlandaquatics.com
1100 Hwy 35 Ocean Plaza Ocean, New Jersey 07712 732.922.2300 Established in 1961, Tropiquarium is one of the oldest and largest aquarium stores in New Jersey.
Largest selection of cultured marines on the planet! 40,000 gallon facility open to the public Tuesday Through Sunday
24 Bursen Street Rochester, NY 14609 www.caribbeanforest.com 260+ aquariums, largest selection of reef aquariums in Tennessee. Specializing in service, selection, quality and cleanliness since 1986.
T o list Y OUR ST O R E P lea se cont act J ames L aw r ence 802-98 5-9977 x 7
W e w ill need t he f o
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4853 Monroe Street Toledo, OH 43623 www.TrilbyTropicals.com Independently owned with great livestock and all the leading brands for successful reefkeeping: Tropic Marin, Carib Sea, Seachem, Eheim, Sera, and more.
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Pay ment by c re dit c ar d or Pay P al f or �r st issue, billed at eac h issue dat e t her eaf te r . 30 day s net CORAL 95 .
reef life |
DENISE NIELS EN TACKETT
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