Few marine aquarium fish make suitable choices for reef tanks, community fish tanks and species tanks. Tangs fit the bill on all accounts. Largely vegetarian, they seldom bother corals or other delicate invertebrates. Aggressive enough for a community of angelfishes, damsels and wrasses, they nevertheless mix well with smaller, more retiring species such as fairy basslets. Hobbyists with large tanks can enjoy tangs in their natural social arrangement, shoals of several to many individuals.
The yellow tang (Zebrasoma flavescens) reaches a diameter of nearly 8 inches in the sea; aquarium specimens seldom exceed 6 inches. Nevertheless, provide a tank 4 feet or more in length for these active swimmers.
In the reef aquarium, the yellow tang earns its keep by grazing on filamentous algae, helping to keep the rocks and decorations free of excessive growth.
Although large, well-established specimens may be aggressive, particularly under crowded conditions or in a tank that is too small to make them feel comfortable, this species seldom presents a behavior problem. Therefore, yellow tangs can be housed with most other fish, including smaller species. Because these fish are not predatory toward other fish, they are suitable for community displays. In the tank tangs feed almost exclusively on algae and small invertebrates.
Normally found in loose aggregations of two to many individuals, if you introduce all specimens into the aquarium at the same time, they get along fine. As the focus of a species tank, nothing rivals a group of yellow tangs. They display both a stunning color and active behaviors. The species aquarium, however, must be large. I recommend nothing less than a 6-foot-long, 125-gallon tank or larger.
Yellow tangs are found in much of the Pacific, occurring from Japan to Hawaii north of the equator. Typically, they live on outer reefs with dense coral stands, most commonly of the branching genera Acropora and Pocillopora. These fish may also be found in lagoons. Yellow tangs range in water depths of about 10 feet to more than 100 feet.
Conditions in a yellow tang’s habitat remain relatively constant, in terms of salinity, temperature, sun exposure and turbulence. Naturally, stability of aquarium conditions figure prominently in their basic husbandry needs.
Like other Zebrasoma, the body of the yellow tang is disk-shaped, with a short, protruding snout filled with sharp teeth adapted for grazing algae. Uniformly lemon yellow in coloration by day, in darkness yellow tangs adopt a “sleep” color pattern — pale pinkish yellow — with a prominent midlateral white stripe. I’ve received calls from worried aquarists who, after observing yellows first thing in the morning, assume the resting coloration indicates a serious health problem. After the lights have been on for a short while, however, their brilliant yellow coloration returns.
Like all tangs, Z. flavescens has a razor-sharp scale on the caudal peduncle. Used both defensively and offensively when the fish defends its territory, this specialized scale gives the group its name. The “tang” part of a knife consists of the portion of the blade that extends into the handle, usually hidden from view. Pearly white in coloration, the yellow tang’s “tang” can be easily discerned against the background of its brilliant yellow body. The actual weapon folds away into a groove on the caudal peduncle, much like the blade of a jackknife. A white spot marks its place and acts as a warning to other fish of its defensive nature. Would-be aggressors seem to heed the warning. Likewise, aquarists should avoid catching tangs in nets. Tangs will either shred a net or become entangled and possibly injured by one. Common sense also suggests avoiding this razor-sharp weapon whenever handling a tang. It can inflict a nasty wound.
Achilles tang (Acanthurus achilles). These tangs inhabit turbulent water and graze heavily on algae. They often fare poorly in aquariums with low water movement. Best left for expert aquarists.
Chevron tang (Ctenochaetus hawaiiensis). A combtooth tang that is highly sought after because it feeds on filamentous algae. It adapts to the aquarium provided algae grows in sufficient abundance.
Kole or goldeye tang (Ctenochaetus strigosus). Another combtooth that loves filamentous algae and is quite adaptable to the home aquarium. Both it and chevrons range throughout the Indo-Pacific oceanic region.
Lipstick tang (Naso lituratus). These gaudily colored cousins of achilles must have brown algae (e.g., kelp) in their diet in order to survive more than a few months. Again, a species for advanced aquarists.
Powder blue tang (Acanthurus leucosternon). Another species often collected using cyanide, this species commands a high price. Therefore, individuals need to exercise good judgment when choosing a specimen.
Regal tang (Paracanthurus hepatus). These attractive fish have a distinctive true-blue color with a yellow tail. A sickle-shaped black bar on the side completes the dramatic appearance of this handsome fish. Found almost exclusively in association with the stony coral Pocillopora, on the seaward side of reefs, this fish has a habit of wedging itself into the coral and lying flat on its side. Its propensity to do this in the aquarium has given pause to more than one novice aquarist. Unfortunately, too many of these fish have been collected by poisoning the entire coral head. Regals are good candidates for cyanide problems, so know your supplier before you purchase one.
Sailfin tang (Zebrasoma veliferum). These are commonly imported and have precisely the same care requirements as the yellow tang and can substitute for it in any aquarium situation. Vertical black bars running from the top of the dorsal fin to the bottom of the anal fin serve to make this tang look even larger and more impressive than the yellow tang. Its coloration seldom commands the same attention as the yellows, however.
Zebrasoma species (a total of seven species occur in the Indo-Pacific realm) hold their large dorsal and anal fins erect when danger threatens. Apparently, this behavior makes the fish look larger to a potential predator or rival that happens by. Juvenile specimens often appear twice as large as their actual size, and they probably benefit more from the deception than adults do.
Most Zebrasoma are found in relatively small groups of only five or six individuals. And this appears to be true for Z. flavescens over most of its range. Much larger aggregations of Z. flavescens occur in Hawaii, from which collectors harvest numerous aquarium specimens. I suggest purchasing only specimens that you know to have been collected from Hawaii. Not only are they relatively inexpensive, but their condition is likely to be superior to that of individuals harvested anywhere in Asia.
Because of their popularity and the complex nature of their favored habitat, which makes collecting difficult, yellow tangs are often caught by unscrupulous fishermen who use cyanide to stun them and make them easier to catch.
Additional Care Information
Feeding yellow tangs, or any of their cousins, should pose few problems, as they not only crop algae from the rocks and coral, but also greedily accept many popular and widely available aquarium foods. Numerous commercially available diets contain a high proportion of vegetable matter, and these should be your first choice for tang staple food. Supplement the greens with small amounts of animal-derived foods, or simply allow your tangs to snatch what they want when you feed the other fish in your tank.
Always make sure that your tangs’ stomachs appear full and round. A hollow-bellied specimen needs immediate attention — because this is a sure sign of acute starvation.
Grazing species like the yellow tang often feed nearly continuously during daylight hours. Continuous feeding may not be practical in captivity, but two or three daily feedings, along with any natural algae growth in the aquarium, should suffice. Do not make the mistake of feeding tangs exclusively on greens such as lettuce or spinach. While acceptable from time to time, such foods may lead to deficiencies. A tang’s diet should include ocean-derived vegetable material. This shouldn’t pose that much of a problem, because most commercial products contain marine algae.
Plant-derived food provides fewer nutrients per gram consumed than animal-derived food, as a general rule. Thus, a vegetarian fish expends a lot of energy just moving around from place to place in search of something to eat. This is why it is important to give tangs and other vegetarians ample fare. Ideally, they should have access to food throughout the day. Smaller individuals can be especially prone to the effects of malnutrition in a surprisingly short time. Therefore, you should choose specimens that are at least 3 inches in diameter.
Yellow tangs rarely spawn in captivity, but spawning has been observed in the sea on repeated occasions. Generally, they spawn in groups around sunset, milling about, their activities increase until a female dashes toward the surface with one or several males in pursuit. Eggs and sperm are released, fertilization occurs and the developing embryos are left to fend for themselves.
The hardiness of yellow tangs is legendary, but they succumb quickly to declining water quality. This is to be expected, considering that their preferred habitat is constantly replenished from the open sea. Failure to carry out regular partial water changes is often responsible for health problems with this species. Sick tangs develop reddish, inflamed patches on their skin, a sure sign that water conditions are less than optimum.
Whether this is due to the accumulation of dissolved organics, metals, some other substance, or a combination, the condition may be reliably reversed by carrying out a large water change. Activated carbon filtration will not by itself remedy the problem, unfortunately.
Left untended, a tang that exhibits this inflammation will often soon develop Cryptocaryon, Amyloodinium or a combination of both of these parasitic infestations. Without an immediate improvement in water quality and a regimen of medication, fatalities are often the result.
With attention to water quality and a proper diet, yellow tangs can live five to 10 years in the aquarium. Its bright coloration, hardiness, ease of feeding and adaptability to various aquarium situations are no doubt responsible for its enormous popularity for the past 25-plus years. Given attention to their simple requirements, there is no reason why hobbyists should not be able to maintain these beautiful fish for a similar period.