Hawaiian Cleaner Wrasse

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290 Natural Reef Aquariums these two extremes. These may constitute the majority of species in old, stable ecosystems such as the Great Smoky Mountains. When their habitat is disturbed in some way, perhaps by a forest fire, the pattern of species that results as the ecosystem recovers from disturbance often reveals the basic strategy of these "middle of the road" species. Nature rarely, if ever, fits precisely into human-defined categories.

What does this have to do with reef aquariums? Only that the species that usually do best in captivity are either r-selected species or those k-selected species whose habitat requirements are clearly understood. Aquarium hobbyists, particularly novices, should be aware that some species are on the market whose chances of survival in captivity are slim. Just because a specimen is swimming in a dealer's tank does not mean that it will continue to accommodate itself to an artificial habitat as readily as might another species swimming alongside it. Attempts to categorize marine aquarium fishes to identify those that typically have a high likelihood of survival and those that do not have been met with varying degrees of acceptance by hobbyists and those in the industry. While few disagree that life-history information should be made widely available, the idea of categorizing species into broad "suitable" or "unsuitable" lists is controversial. Oversimplification in such listings can easily lead to misunderstandings.

On the other hand, it does seem appropriate to create some rules of thumb that could make it easier for hobbyists to decide whether a species should or should not be at-these species, a lifetime is measured in centuries. The giant tempted. Whether or not dealers use such categories to

Orange Fin Batfish

A difficult-to-feed species, the Red-finned Batfish CPlatax pin-natus) typically perishes within months in home aquariums.

redwood is an oft-mentioned example.

choose which species to stock, market forces, driven by hob-

It is tempting to draw conclusions about the implica- byists' collective buying decisions, will ultimately deter-

tions for human behavior such observations suggest. One mine whether or not a given species remains in the must remember, however, that both strategies succeed, be- aquarium trade. This is an alternative far preferable to at-

cause the criterion for success is longevity of the species, not tempts by government regulators to control the importation of the individual.

of aquarium specimens, if the experiences of other coun-Some species, of course, fall somewhere in between tries are any indication. In Germany, the government's re-

Chapter Fourteen 291

sponse to environmentalists' complaints about the continued importation of certain butterflyfishes was to place off limits the entire Family Chaetodontidae. But this was an oversimplification. Despite their general reputation for delicacy some of the best aquarium species are butterflyfishes. These appropriate species, unfortunately, were also included in the ban. Hobbyists and dealers in the United States are justifiably concerned that any government regulators here will be equally myopic. Hence some are opposed to the kind of listmaking found in this chapter.

Nevertheless, I believe we must begin the educational process somewhere. Herewith are nine categories of selected species that I prefer to designate "of special concern" to hobbyists. In each case, one or more aspects of their ecology currently render them less easily maintained in a typical All of the obligate cleaners, such as this Hawaiian Cleaner home-based aquarium. Consider these facts carefully before Wrasse (Labroides phthirophagus), are best left in the wild purchasing these species.

Cleaner Wrasse


The species is protected in its native habitat.

fauna of the kelp forest, one might then inquire as to the legal availability of this species. It is out of place, however, in the warm water of a tropical reef tank. The King Angelfish (Hoiacanthus passer) is protected in a portion of its home It should be obvious that all collecting of aquarium range, but aquarium specimens are legally collected in other specimens must be done in accordance with local environ- areas. (Hence the importance of knowing where a specimen mental regulations, but hobbyists should be aware that some originated.) The aquarium-fish hobby has a generally good protected species are still collected. I suspect Caribbean stony reputation for not trading in illegal species, and I think we corals are subject to poaching. My company has received can all play a role in never encouraging the collection of numerous requests for sea dragons, such as Phycodurus eques, banned or questionable livestock, and Phyllopteryx taeniolatus, which are protected in their native Australia. Other members of the Family Syngnathidae, to which sea dragons belong, pose special problems for aquarists (see Category 8). Perhaps the most commonly seen species that may be poached from restricted waters is the

Category 2

Removal of this species is demonstrably detrimental to other reef speciesy i.e., this is a "key" species in its habitat.

Garibaldi Damselfish (Hypsypops rubicunda), found in the Species that exhibit cleaning behavior, and that kelp forests off the southern California coast. This is a cool- are locally rare, may fall into this category. Key species are water species that is often inappropriately maintained. If often the subjects of ecological research, but I know of no one were considering an aquarium display depicting the study that examines the impact of collection of cleaner

292 Natural Reef Aquariums species, for example, for the aquarium trade. Perhaps of

Among the sharks often sold for aquariums are the more concern than mere removal is the fate of such species leopard sharks (Triakis spp.) the wobbegongs (Orectolobus once collected. If a potentially key species is also one that spp.) and, most commonly, the Nurse Shark (Gingly mo stoma fails to survive readily in captivity, a stronger argument for cirratum). Nurse Sharks, so named because they produce a abstaining from collecting it can be made. Obligate clean- sucking sound when feeding (like the sound of a child nurs-

ers, such as the Hawaiian Cleaner Wrasse (Labroidesphthi- ing) are frequently sold to aquarium shops shortly after rophagus) seldom survive for long in the aquarium. Further, birth, when they are about 24 inches in length. In a few this species is endemic, meaning it is found only in the years' time, the fish will have grown to a 4-foot specimen

Hawaiian archipelago.

that is unable to turn around in a 300-gallon tank. Nine-

The Magnificent Anemone (Heteractis magnifica) is sel- foot Nurse Sharks are not uncommon in the waters of the dom amenable to aquarium care and represents another ex- Caribbean and Florida.

ample of a potentially key species. Since the population of

Rays are members of the shark clan adapted to life on clownfishes in a given area is directly tied to the abundance the bottom. Spotted rays (Taeniura spp.) and stingrays of these anemones, reducing the anemone population may (Dasyatis americana, for example) need broad expanses of have consequences for the clownfish population, especially sandy bottom and may grow to several feet in diameter, since the anemones are slow-growing, long-lived, and have Stingrays, of course, have venomous spines they use for de-

few offspring.

fense, another potential deterrent to the home hobbyist (see Category 5).

Category 3

The species grows too large for the typical home aquarium.

Category 4

The species is aggressive and territorial.

Many species of sharks and rays (Order Elasmo- Anyone, of course, can end up with a fish like this, branchi), for example, grow too large for standard home The King Angelfish (Holacanthuspasser) can cause prob-

aquariums. Unsuspecting aquarists, when faced with the lems, as can many members of Family Balistidae, the trig-

question of what to do with an overgrown shark, often turn gerfishes. Any large triggerfish has powerful jaws and sharp to public aquariums for help. Only rarely is the public aquar- teeth. As they grow, their aggressive tendencies become ium able to accommodate the specimen. Other big preda- more apparent. The Queen Triggerfish (Batistes vetula) is tors pose similar problems. Always find out the adult size among the largest — and nastiest — of its family. I know of any prospective aquarium specimen.

of one diver who lost a thumb to a Queen Trigger in the

Many sharks are k-selected species that mature late and Florida Keys. Another trigger with a nasty disposition is the

Undulated Triggerfish (Balistapus undulatus).

Aggressive fish must often have an entire aquarium de-of attention from marine ecologists. Look for shark fish- voted to them, but do frequently have the advantage of being, as well as collection of live sharks for aquariums, to re- ing extremely hardy and undemanding. If this is your goal, many siiaiKS are K-seiecieu species mai niaiuie laic anu have few young. Because of their important role at the top of many food chains, sharks are receiving a growing amount ceive regulatory scrutiny in the near future.

so be it, but keep your hands out of the tank.

Chapter Fourteen 293

Category 5

The species is venomous.

show up in Indo-Pacific shipments should always be handled with care until positive identification can be made. Several sea urchins are capable of delivering a venomous "bite"

"Venom" refers to a poison that is introduced into with specially modified appendages. Because of the appear-

the body of another organism by means of a weapon of some ance of these structures, venomous urchins are sometimes la-

kind — fangs, for example, or a stinger. Like aggressive- beled "Flower Urchins" in the trade. They should be handled ness, the possession of venom does not make a species un- with extreme caution. The long-spined sea urchins (Di-

suitable for aquarium life, but this trait must be considered adema spp.) are prickly, but impaling oneself with a spine, by any prudent person. The presence of small children in the though painful, is hardly a serious injury. Diadema antil-

home might rule out the keeping of venomous species. Lionfishes, Family Scorpaenidae, are splendid aquarium larum specimens are protected from collection in some areas. Some fish are not venomous, but they are toxic, mean-

fishes, even though they have venomous spines. Genera in ing that their flesh, if eaten, is harmful to the predator.

this family include Dendrochirus, Pterois, and Inimicus.

Among these are the puffers, Family Tetraodontidae, which

A closely related subfamily, Synanceiinae, the stone- number human beings among the species that have died fishes, includes species that have caused human deaths from consuming their flesh. So, too, do the dragonets, Fam-

Contact with the dorsal spines of a Synanceia species has ily Callionymidae, protect themselves from harm. Neither been known to result in such excruciating pain that victims of these families is prone to cause problems in the aquarium, have amputated their own limbs to achieve relief.

Less frightening are the foxfaces, Family Siganidae, including species of Siganus and, most commonly in the aquarium trade, Siganus vulpinus, the Common Foxface. These herbivorous grazers are armed with venomous dorsal spines. Contact feels much like a bee sting, according to reports from vic tims. Similarly, the Coral Catfish (Plotosus lineatus) shares with some of its freshwater cousins the possession of a barbed, venomous pectoral fin spine. Black with longitudinal yellow stripes, these fish are cute as juveniles, when they gather into a school. As they grow, they change color to a drab gray, become solitary and aggressive, and are not cute at all.

Among invertebrates, the Blue-ringed Octopus (Hapalochlaena lunulata and H. maculosa) can administer a deadly bite, as can many species of cone snails (Conus). Many other Conus species can sting, Worthy of care but not for children's tanks are venomous species though not fatally. Brightly colored mollusks that such as this Tassled Scorpionfish (Scorpaenopsis oxycephala).

Scorpion Fish Sting

294 Natural Reef Aquariums however, and several species are widely kept. On the other hand, boxfishes and trunkfishes, Family Ostraciidae, all are able to exude a toxin that is deadly even to themselves in the confines of an aquarium. Toxin secretion is a response to stress, so careful consideration should be given to including these species in a community aquarium. Cowfishes (Lactoria spp.) are among the most commonly imported members of this clan.

Another kind of "venom" is the ability to produce an electric shock. The Electric Ray (Narcine brasiliensis) reaches only 18 inches, but reportedly can generate a shock sufficient to knock down a human.

Category 6

The natural lifespan of the species is brief

Inclusion of this category has more to do with consumer education than with reef conservation. Species with a brief lifespan are often r-selected and are so abundant that removal of a few specimens from a given area will have little significance. A short lifespan can actually be advantageous in an aquarium species, as such species typically grow

Cone Snail Lifespan

Truly flamboyant, most nudibranchs, such as Chromodoris bullocki, have extremely short lifespans, even in the wild.

Category 7

Special requirements for this species, usually dietary needs, cannot be met by the home aquarist. Appropriate conditions for keeping this species are not yet defined.

rapidly, mature early and have many offspring.This is what This is the largest category and contains the has made killifish, including annual types that live only a greatest number of species regularly seen in the aquarium few months, popular with a segment of the freshwater trade. These species should not be dogmatically regarded aquarium hobby. Nevertheless, many hobbyists are disap- as "impossible." Rather, they should be regarded as appro-

pointed to find out after the fact that the seemingly un- priate subjects for research into methods for their success-

timely death of a specimen is normal for that species. The ful captive husbandry. Who should or should not be species most often generating these kinds of complaints, and permitted to acquire such species for this purpose, of course, their approximate natural lifespans, are:

• Octopuses: survive 1 to 3 years, depending upon the species; females invariably die after the young hatch.

remains an open and politically touchy question.

Chief among the species with specialized dietary requirements are the butterflyfishes, Family Chaetodontidae.

Seahorses: survive 1 to 3 years; require appropriate While there are butterflyfishes that adapt readily to aquarium diets, the species listed in Table 14-1 (page 296) usu-

live foods.

Nudibranchs and sea slugs: smaller species usually live ally do not. Most of them feed on stony-coral polyps or a year at most; may be very difficult to feed. other sessile invertebrates and will starve rather than ac-

Chapter Fourteen 295

cept an unfamiliar food. The Short-bodied Blenny (.Exallias a large proportion of benthic invertebrates, sponges in par-brevis) and the Orange-spotted Filefish (Oxymonacanthus ticular, and some species may not fare well without these longirostris) share this trait with the butterflyfishes.

foods. In some cases, specimens collected as large juveniles

Other tastes are more exotic. Mimic blennies (Pla- seem to adapt best to aquarium diets, while smaller or larger giotremus spp.) feed by dashing out and tearing bits o: flesh individuals do not. The Rock Beauty (.Holacanthus tricolor)

from other fishes. Some have evolved elaborate disguises, fits this description. This may be because the natural di-

usually contriving to look like harmless species. For the etary preferences of the juvenile differ from those of the wrasses listed in Table 14-1, food items are as varied as poly- adult. Another sponge-eating fish that does not survive well chaete worms, benthic invertebrates, and parasites picked under aquarium conditions is the Moorish Idol (Zanclus cor-

from the bodies of other fishes. The Red-finned Batfish nutus). A specimen maintained in my office died after about

(.Plataxpinnatus) often lives around mangrove roots where a year, for no apparent reason, despite appropriate water it feeds on a multitude of encrusting invertebrates. While conditions and a varied diet, including a commercial food this species may sometimes learn to feed on shrimp or other claimed to contain marine sponges. Shrimpfishes are tiny foods in the aquarium, it seldom lives longer than a few and generally spend their lives hanging nose down among months. The Clown Sweetlips (Plectorhinchus chaeto- the spines of a sea urchin. They require minuscule live foods dontoides), which mimics a toxic invertebrate and is per to survive. Some species of parrotfishes feed by biting off haps toxic itself, feeds at night on a variety of living chunks of living coral, digesting the polyps and excreting invertebrates and generally refuses to eat in the aquarium. coral sand. Others feed only on leafy sea grasses. Neither The dietary requirements of angelfishes apparently include type survives well on captive diets.

An interesting subset of this group of species are those that public aquariums were unable to maintain successfully for a year or more. (Hutchins, et al., 1994) This list is reproduced as Table 14-2 (page 298). Note that the same species appear again and again on lists such as this, irrespective of the compiler.

Invertebrates with specialized food needs include most nudibranchs and sea slugs. Flamingo tongue snails (Cyphoma spp.) all feed exclusively on gorgonians.

As explained in Chapter Twelve, some fishes may not adapt to aquarium life because the appropriate social milieu cannot be provided. This may be one reason why cleaner wrasses, such as the common Labroides dimidiatus, so often fail to thrive. Similarly, tilefishes (Family Malacanthidae)

fare poorly because in nature they are seldom far from their burrow in the sand, into which they dart immediately at any sign of danger. The often-imported Purple Tilefish

Calcareous Sponge

Evolved to feed on calcareous sponges, this nudibranch CNotodoris minor) is destined to starve in captive systems

296 Natural Reef Aquariums

Table 14-1

fishes with Special Dietary Needs


Aspidontus spp. Exallias brevis Plagiotremus spp. Centriscidae

Mimic Blennies Short-bodied Blenny Mimic Blennies


Plectorhinchus chaetodontoides Clown Sweetlips Labridae

Anampses spp. Labroides phthirophagus

Tamarin Wrasses Hawaiian Cleaner Wrasse

Aeoliscus spp.


Labropsis spp.

Tube-Lip Wrasses

Centriscus spp.


Macropharyngodon spp.

Leopard Wrasses


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  • Klaus
    Do cleaner wrasses cause problems?
    8 years ago

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