Ask the WWM Crew
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The source: Hawaiian yellow tangs mostly originate from the Big Island of the chains namesake. With some 4,038 square miles this island is about the size of Connecticut. The isle (singular) of Hawaii is Big, more than twice the size of all the other Hawaiian Islands combined. The second largest cattle ranch in the United States, the Parker is there, with more than 200,000 acres.
Yellow tangs are found all around its circumference from shallows (see photograph) to about 120 feet.
A Problem, Brah?
There is a tremendous amount of enmity on the Big Island (where virtually all of Hawaii's yellow tangs originate) between the sport diving/tourist industry and the pet-fish collection business. The former accuses the latter of significantly reducing fish populations and damaging the environment. Fish collectors are of the general consensus that they have little impact. I have to side with them.
According to official records some half a million fishes are exported from the Big Island annually, of which about half are yellow tangs. Are there less fishes at present than the last ten, twenty years. Let's take a realistic look at this; five hundred thousand individual organisms per year is close to 1,370 fishes per day. At a couple of ounces each this comes out to some one hundred seventy one pounds. Compare this with the thousands of food fishes, of tens of thousands of pounds, including many that are kept as ornament (tangs, triggers, Parrotfishes...) taken for human consumption daily.
Also consider; some locals and scientists have suggested that the 1984 to present lava flows from Kilauea Volcano may be a contributor to losses. The millions of cubic yards of molten rock include noxious sources of sulfur, nitrogen and hydrogen that go into solution as runoff and enter directly into the sea as lava. Such flows have added some four to five hundred new acres of land, reaching the sea.
Other probable sources of mortality are obvious to anyone swimming in the surrounding waters. The fuel aerosol from planes, washout from boat motors and street runoff. Oil from road asphalt, soaps and detergents et al. make their way via storm and sewage outfalls to the sea.
I don't accept or understand the animosity betwixt the tourism diving biz and tropical fish collectors. They need each other, directly. Curiosity and enjoyment of the living world on the part of one stimulates interest in the other. Secondly, and more important in the long haul is their need to bind together to challenge some of the prominent "environmental" control-freak organizations. Several of these mis- and dis-informing groups would love to shut down both our hobby and sport diving.
The yellow tang is not a diminished or declining resource as a consequence of aquarium interest. People who want to make a real less negative impact on the Environment are encouraged to examine their patterns of consumption, skip having children, campaign against excessive government...
The yellow tang, Zebrasoma flavescens is a wonderful marine "fish tank" species. It feeds well on all foods, has wide environmental tolerance and disease resistance. Beginning hobbyists and service accounts have real Kona gold in the yellow tang. Buy them from Hawaii.
Zebrasoma flavescens itself:
Yellow tangs are surgeonfish (family Acanthuridae) par excellence. As far as the group goes they are relatively easygoing tankmates, adapting much better to the small spaces which we call aquariums. Until recently they were also amongst the least expensive marines, retailing for U.S. $15.00-25.00 nationwide.
Found in the Pacific; principally the Hawaiian Islands, where it is the number one tropical marine fish export. Also found from in the western Pacific; Ryukyu, Mariana, Marshall Islands, Marcus and Wake.
Surgeons, tangs or Doctorfishes ("Ah-kan-thur-id-ee") are a worldwide tropical assemblage. Their common and scientific naming alludes to the presence and use of process(es) on the caudal peduncle; one or more scalpel-like blades. In the yellow tang genus Zebrasoma this spine can be folded to the side.
The several tang species offered in the hobby trade range from a few to several inches in length. Most species live amongst shallow rocky and coral reefs. The larger varieties are more free-ranging, a few even considered open ocean pelagics. Did you know there are some more open ocean/pelagic types that get to be more than two feet long? Unless you have a system of tens of thousands of gallons you'll have to skip those.
Foods, Feeding Nutrition:
All tangs are herbivorous to a degree. Observing yellow tangs in the wild and aquariums, and examining their stomach contents has shown that they ingest principally micro-algae, secondarily macro-algae, and that the bulk of the rest is material (associated invertebrates, fish eggs) taken incidental to these. In captivity surgeons require regular offerings of 'greens'. Vegetable flake, pellet and frozen prepared foods are to be had in pet fish stores; better and cheaper are dried and fresh algae from the oriental sections of human food stores. The very best opportunity is to provide some live material that your tangs can nibble on at their leisure. Though others endorse their use, I am very unimpressed with the results of feeding lettuces, boiled, frozen or fricasseed to surgeons. Be leery of relying on terrestrial plants for marine fish nutrition.
Where yellow tangs are concerned, picking out the one's you want comes down to consideration of three criteria: 1) Index of fitness, 2) Behavior, 3) Color.
(1) Healthy specimens are full-bodied, in particular in the head area above the eyes should not have a pinched-in appearance. Having captured these fish (they're easy) I don't think they are cyanided for collection in non-Hawaiian places. Instead I attribute the differential mortality observed from these sources versus Hawaii to the extended time that passes from collection, holding, transport to wholesale transhippers over and through stateside. This takes several days to a few weeks. If watching tangs in the wild teaches you anything, it is that they feed continuously. When deprived of grazing yellows fade to thinness and pale color, at some point giving up on feeding altogether.
(2) Behavior is very telling with surgeons. Healthy yellow tangs are curious about their surroundings. Buy ones that are checking you and their tank out.
(3) Color wise yellow tangs are yellow; golden, deep yellow. Every now and then you may find a brownish or yellow-white morph, and their is a fright and night time coloration that involves a white vertical body band. You don't want these; go for the gold.
Be very wary of flavescens tangs that exhibit any red markings. Look especially close at the fin origins and 'tang' near the tail for signs of fouling/tearing in net-mis-handling. Surgeons should be moved by 'herding' into a bag, bowl, specimen container; not lifted in nets.
Filtration & Circulation:
Should be in a word, vigorous. These fishes live in high motion waters with near saturation oxygen. Surgeons eat & defecate large quantities yet are intolerant of waste build-up. Adequate filtration coupled with frequent partial water changes are requisite.
Inter and Intra-specific Aggression:
Yellow tangs are almost ideal tankmates. Except for other flavescens tangs about the same size they get along very well with most all other fishes. Personal exceptions include other tangs, mainly those in the genus Zebrasoma; considered a mechanism to delimit crowding in grazing areas. Therefore, under crowding is always the safest bet, followed by introduction of smaller individuals first. Careful observation is a hallmark of a conscientious aquarist.
The acanthus or thorny spine at the yellow tangs caudal peduncle is a formidable weapon, which they can and will unsheathe and use. Yellows will not bother smaller or larger fishes unless provoked; and then mainly for show rather than slash.
Other larger predatory fishes will eat mouth-size tangs. I've seen small one's used as bait by fisherman in the tropics.
Yellow tangs are readily susceptible to the common protozoan infections of marine fishes, and happily easily treated by common methods. Additionally, they are susceptible to a peculiar flatworm infestation; so-called black dot disease.
Yellow tangs are also notable bio-assay organisms, showing the effects of diminished water quality and/or malnutrition ahead of many other types of organisms. Erosive hole in the head, lateral line, off-feeding... are indicative of low pH, high organics, C avitaminoses. Appropriate set-up, water change, proper foods all prevent this.
Take a look at the accompany graphic(s) with this piece. yellow tangs inhabit rocky and coralline reef areas where they can forage and duck under cover for sleep and safety. Each fish will settle into it's own spot on your artificial arrangement (little buddy), developing general motion patterns, always on the move.
Regarding inclusion of this and other tangs in 'reef tanks'; I don't suggest it. Though these fishes will nibble away at pesky undesirable algae, they do not stop there and have been recorded consuming corals and more. If you must, try a small subject in a large system and keep your eye on them. There are other marine "algae eaters" (gobies, snails, etc.) to augment prevention methods.
The Best Yellow Marine Fish Come on Down:
Maybe you like the canary blenny, juvenile female Coris wrasse or clown goby; for me it's got to be the yellow tang. And the supreme source? Hawaii; where the industry and the environment are protected by U.S. law.
Burgess, W.E. 1979. The genus Zebrasoma. T.F.H. 11/79.
Chlupaty, Peter. 1979. Keeping the yellow tang. T.F.H. 7/89.
Kent, M.I. and A.C. Olson. 1986. Interrelationships of a parasitic turbellarian, (Paravortex sp.) (Grafillidae, Rhabdocoela) and its marine fish hosts. Fish Pathol. 21:65-72.
Michael, S.W. 1992. A guide to the tangs of the genus Zebrasoma. SeaScope Vol. 9 Fall, 1992.
Michael, S.W. 1995. Fishes for the marine aquarium, part 7. Tangs of the genus Zebrasoma. A.F.M. 4/95.