Related Articles: Surgeonfishes, Acanthurus, Ctenochaetus, Naso, Zebrasoma

Marine Aquarium Use of Hawaiian Surgeons, Tangs and Doctorfishes

Bob Fenner

Tang scene in Hawai'i

Surgeonfishes: Tangs for Marine Aquariums
Diversity, Selection & Care
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by Robert (Bob) Fenner

Whatever common name applied to these razor-wielding fishes, the Surgeons, Tangs or Doctorfishes span the entire bandwidth of aquarium suitability. A few ship so poorly they rarely recover from the rigors of capture and transport from the wild. Then there are the members of the family that should be disqualified on the basis of growing too large (quite a few to more than a foot and a half in length), and/or outright agonistic behavior... The majority, though tough as proverbial "nails", must still be qualified as through careful individual selection on the basis of apparent condition and proven feeding.

Not to worry, here we'll sort out which are suitable for aquarium use.

Classification: Taxonomy, Relation with Other Groups

The surgeonfish family Acanthuridae comprises six genera and about seventy two species. Many are important food and aquarium fishes. Where would our hobby be without such favorites as the Yellow Tang and other Zebrasoma, the Yellowtail Blue Paracanthurus, various Naso and Acanthurus and lesser-known Bristlemouth (Ctenochaetus) Surgeonfishes in addition to the Prionurus?

All surgeonfishes are laterally compressed covered with very small scales giving their bodies a leathery appearance. They have long continuous dorsal fins, and small terminal mouths with fine teeth. What really distinguishes the whole family though is the presence of one or more spines on the caudal peduncle (the part of the body right before the tail fin), hence their scientific name from the Greek, acanthus = "thorn". With a twist of the tail these spines are used to as a formidable weapon when needed.

Modern classification schemes divide the six genera of Acanthurids into two subfamilies (names ending in "inae") and three tribes (ending in "ini").

The subfamily Nasinae, with one genus (Naso, the Unicornfishes) and seventeen species have two anal fin spines and three soft pelvic fin rays. Several have a frontal "horn" protuberance that gets larger with age. Four branchiostegal (gill supports) rays.

The subfamily Acanthurinae, the rest of the surgeonfishes, bear three anal fin spines and five soft pelvic fin rays. Five branchiostegal rays.

Tribe Prionurini; one genus (Prionurus), six species, rarely offered in the trade. Have 3-10 non-retractile bony plate "scalpels" on their caudal peduncles.

Tribe Zebrasomini; containing the genera Paracanthurus (one species, the Yellowtail blue), and Zebrasoma of seven species.

The Tribe Acanthurini, genera Acanthurus and Ctenochaetus can be discerned from each other by the six species of Bristlemouths (Ctenochaetus) peculiar long, comb-like teeth.

Surgeonfishes as a family are circumtropical. They are prominent species in shallows to a few hundred feet on rocky and coral reefs worldwide. Most are found in the western Pacific, with only nine species in the Atlantic and four in the eastern Pacific.

Size-wise they are from a few inches to a couple of feet in total length.

Captive Suitability Scoring:

After long thought, investigation of others declared opinions, and handling thousands of these fishes over the last thirty some years in the trade I've come up with the following scheme of "scores" for each on its likelihood of surviving the rigors of aquarium care. To a degree this information is necessarily historical (what has happened, may not be the general trend to come), and is subject to "improvement" on the keepers side as a consequence of providing larger, more stable quarters and more diligent husbandry. But, by and large a relative score of one (1) indicates the "highest and best" survivability under captive conditions; let's say most of the specimens of this species collected surviving more than three months. A score of two (2) is indicative of a mortality of more than fifty percent between one and three months. Lastly, and sufficient for our purposes, a three (3) is the worst score, with more than 50% of the species perishing before a months time of capture. I entreat you to leave the latter group to the sea, or at least to study and provide the best possible circumstances for these animals.

I'm aware that other authors, even highly respected scientists' ratings are different than your dealer(s) and mine probably consider my "judgments" too harsh. My advice is indeed, not to rely on what's stated here and/or any one other source of information. Before purchasing these (or other livestock) do your best to gather as much pertinent "accurate, significant, and meaningful" information as you can from reading, other hobbyists and the industry.

Genus Acanthurus ("Ah-Kan-Thur-Us") Species; the Good, The Bad, and The Unknown:

How many surgeonfishes in the genus Acanthurus do you know? There are Powder Browns (A. nigricans (nee glaucopareius) and A. japonicus), the Powder Blue, Atlantic Blue, Achilles, Oriental... any others? Hey, no cheating by looking below. All told there are some forty described species in this genus; including two "mimics" often mistaken for dwarf angels!

Some Acanthurus make hardy captive specimens, others have a dismal aquarium history; a handful are too poorly known to be judged as yet.

"Good" Hawaiian Acanthurus (One's That Generally Live)(1's):

Acanthurus dussumieri Valenciennes 1835, (Palani) the Eyestripe or Dussumier's Surgeonfish. This is a highly variably colored fish. Some are drab gray, whereas some I've seen from Hawai'i sported brilliant yellow around their body margin with beautiful royal purple highlights. This surgeon is more like the genus Ctenochaetus in its feeding habits, sifting sand and detritus in addition to algae scraping. Specimens off Maui and in an a hobbyist tank. To eighteen inches long in the wild.

Acanthurus nigrofuscus (Forsskal 1775), (ma'i'i'i) the blackish Brown or Spot-Cheeked Surgeonfish. Manageable size (to eight inches), and moderate behavior toward other fishes qualify the Brown Tang as a desirable aquarium species especially as an algae controller.. Unfortunately it is a rather plain fish. Here in Hawai'i.

Acanthurus thompsoni (Fowler 1923), the White-Tailed Surgeonfish, a good name for this species except for its populations in Hawaii which bear no white on their tail areas. Another name for this planktivore is Thompson's Surgeonfish. Though not a striking beauty, this Whitetail tang is a good feeder and stays moderate small (to ten inches). Rarely imported into the trade.

Acanthurus triostegus (Linnaeus 1758), (Manini) Convict Tang or Manini (Hawaiian). One of the best Acanthurus for use in reef tanks for its size, easy going temperament and habit of consuming fine, filamentous algae. Reserved for native Hawaiian use in Hawai'i, but available from elsewhere.

Bad Hawaiian Acanthurus Species:

What makes an Acanthurus tang species bad besides dying easily in captivity. NOT dying easily... but helping your other livestock do so. Honestly, some individuals of the fishes listed below will try to kill all their tankmates. If you are set on trying one of the designated "bad boys", do provide plenty of hiding spaces and tough, tough, tough space-sharers (triggers, basses, morays, puffers)... and even then keep your eye on them.

Acanthurus. achilles Shaw 1803, (paku iku'i) Achilles tang. Widely distributed from Hawaii westward through Micronesia and Melanesia, an area called Oceania. Though the best specimens do hail from U.S.s 50th state success with this species can only be had by securing a healthy specimen, providing a large well-established living space, with high, consistent specific gravity and oxygen concentration. Juvenile (sans red body patch) and adult in Hawai'i.

Acanthurus olivaceus Forster & Schneider 1801, (na'ena'e) the Orange Spot/Shoulder Tang. A hardy fish out of Hawaii and elsewhere, but unfortunately, a behavioral terror in the ranks of A. lineatus. This is an active fish that grows to more than a foot in length. Place only with MEAN tankmates. Adult and juvenile pictured.

Acanthurus (glaucopareius) nigricans (Linnaeus 1758), the Powder Brown or Gold-Rimmed Surgeon, aka the Cat Tang in Hawai'i. The corrected scientific name of this species is A. nigricans (per Randall, 1988); a revision no doubt as unpopular to some as my labeling the species as "bad". The very similar A. japonicus is a far better aquarium fish; A. nigricans rarely lives for more than a few weeks to months in captivity.

Acanthurus leucopareius (Jenkins 1903), (maikoiko) the Whiteband or Whitebar Surgeonfish, tends to be a picky feeder, hard to train off its favored food, filamentous algae. To about eight inches overall length.

The "Unknowns "and Too-Large Acanthurus: Are these good/bad, or otherwise? Who knows. They're not often seen in the trade, or so poorly elucidated that I couldn't, wouldn't, didn't have enough confidence in my opinion to place them in either bad/good categories.

Acanthurus blochii Valenciennes 1835, (pualu) the Ringtail Surgeonfish. A larger (up to seventeen inches) schooling species, often found shoaling over sandy areas. Found widespread throughout the tropical Indo-Pacific. Note the white bar across this species caudal peduncle.

Acanthurus guttatus Forster & Schneider 1801, (api) the Spotted or Mustard Surgeonfish you might easily take for a Sailfin Tang (Zebrasoma) member for its circular outline, broad bars and active swimming behavior. I've encountered mixed results with this species; some batches living well others dying mysteriously. To eleven inches in length.

Acanthurus nigroris Valenciennes 1835, (maiko), the Bluelined Surgeonfish. Good looking, but shy and a bit big at ten inches for aquarium use. Mid-Pacific in distribution. Adult and close-up of one scraping algae off Oahu.

Acanthurus xanthopterus Valenciennes 1835, (pualu) the Yellowfin Surgeonfish. Similar to the Ringtail and Eyestripe Surgeonfishes, but lacks the other two's light caudal coloration. This is the largest member of the genus Acanthurus, to about 22 inches long.

The genus Ctenochaetus ("ten-oh-key-tus")

The members of this genus are attractively shaped, colorfully marked, and interesting behaviorally... why then doesn't the industry import them more often? Are they uncommon in the wild? Are they too hard to catch? The honest answers; Ctenochaetus aren't rare or difficult to herd into barrier nets; but hobbyists have not had "much luck" historically in keeping these tang species alive. The principal reasons for this are damage in capture and handling, and starvation once the hobbyists get them. Given the selection of initially healthy specimens and provision of algae and detritus (an older, established, not-too-clean) system, especially one with live rock, these fishes are all 1's.

Some pertinent notes regarding the four species of Ctenochaetus occasionally offered in the trade:

Ctenochaetus hawaiiensis Randall 1955, the Chevron Tang (2); All Ctenochaetus species change color with age but the chevron is most striking. C. hawaiiensis young are unforgettable; bold orange bodied covered with variegated lines of electric blue. Adults shift to a deeper orange red base covered with darkish blue uneven horizontal lines, ultimately to almost black (another common name, the Black Surgeonfish). Adult and juvenile shown.

Ctenochaetus strigosus (Bennett 1928), (Kole) the Yellow-eyed or Kole Tang (2); since this and the Chevron Tangs range encompass the principal islands of Hawaii they are the principal species utilized in the West *(though the Kole is found from all the way over in the Indian Ocean). The Kole ("coal-ay") is more shallow water, surface to sixty feet or so, and the Chevron is generally collected in fifty feet plus depths.

Genus Naso Tangs

Just how many unicorn or Naso tangs are there? Most everyone knows the Naso, or lipstick surgeon, Naso lituratus, but there are at least sixteen other species. All these "Naso" tangs share the traits of being open, active swimmers, surgeonfish "spines", and a propensity for getting BIG.

Genus Naso ("Nay-zoh") for the most part are unknown to hobbyists with the exception of N. lituratus. Though this celebrated species is the acknowledged "pick of the litter" in color and markings, there are some other worthwhile Nasos.

Unicornfishes come in slender, tubular shapes, as well as more typical flattened "Acanthurus" form; with or without "horns", all Naso species have similar care. Here I'll expand only on the five that are principally available in the hobby worldwide. All I rate as 2's.

Naso brevirostris (Valenciennes 1835), (kala lolo) sometimes called the Shortnose Unicorn Tang, is mis-named both scientifically and colloquially; it has a long nose as an adult. There are Naso species with much shorter, even absent the "horn" on the head. This grayish-green bodied fish is occasionally imported from Hawaii and the Indo-Pacific.

Naso hexacanthus (Bleeker 1855), (kala lolo, opelu kala) Sleek Unicornfish. Indo-Pacific species... to about 30 inches in length. Not kept in home aquariums... as are other too-large Naso species from these islands. Neither males nor females develop a horn; but do have black tongues!

Naso lituratus (Bleeker 1855), (kala lolo, opelu kala) the Naso tang to most aquarists; it is also known as the tricolor or lipstick tang. There are some who claim that "blonde" and "streamer" versions are different species; they're all Naso lituratus. To eighteen inches in the wild.

Naso unicornis (Forsskal 1775), (kala) the Bluespine, Large or Bignose Unicornfish, is a deep-bodied species that develops a prominent rostral horn starting at about five inches length. The body is light olive to gray with yellowish highlights on the abdomen; to more than two feet. Adult and juvenile shown.

Genus Zebrasoma Tangs:

Of all the genera of surgeonfishes, the seven species of Zebrasoma rank supreme. The Naso tangs? They get too big. Acanthurus? Most are way too feisty for their tankmates' good. Prionurus; also overly large; mean... and venomous! The Yellowtail Blue (Paracanthurus) and Bristlemouths (Ctenochaetus) are good as well, I guess...

Ah, but the Zebrasoma tangs: hardy, beautiful, semi-peaceful all. These disc-shaped surgeons are the most adaptable of the family; readily taking all sorts of aquarium foods, adjusting to the small volumes which are aquariums; highest in disease resistance and treat-ability.

The Zebrasoma comprise seven species of pointed-snout, disc-like bodied, sail-like finned, single peduncle-spined fishes. Their "tangs" are movable; and yes, they know how to use them.

Species on Review:

Zebrasoma flavescens (Bennett 1828), (lau'ipala) the Yellow Sailfin Tang. This is a "standard" in the marine aquarium hobby if there ever was one. Only certain damselfish species grace the tanks of aquarists more than Z. flavescens. To plate size, eight inches, in the wild.

Our old service company used to have a Yellow Tang in most every saltwater account. With their conspicuous golden yellow color, active, skipping-like swimming and hardy nature, yellows made long-term customer pleasing additions. Ours came from the U.S. Fiftieth State. The Yellow Sailfin Tang makes up the bulk of pet-fish collected out of Hawai'i, and rightly so. It is best from there.

Zebrasoma veliferum (Bloch 1797), (maneoneo) the Pacific Sailfin Tang. Collected out of the Philippines and Indonesia, though better out of Hawaii, Ceylon and other places in the eastern Pacific. Some call this THE Sailfin tang for it's gorgeous flowing dorsal and anal finnage; these especially over-sized in appearance when young. To 15 inches long in the wild.

Close:

Surgeonfishes span the range of usefulness and adaptability for captive marine systems. The ones in Hawai'i likewise. Some species are relatively tough environmentally, and easy-going in terms of other livestock. Others get too big, and/or territorial, and have proven to be difficult for all but the most attentive aquarists with large, optimized systems.

Other than picking out the better/best species and specimens for your use, successful Hawaiian surgeon care is assured through providing adequate space, aged, highly circulated and aerated water, and constant provision of appropriate foods (mainly greens that are best provided as a mix of macro-algae and live rock.)

Bibliography/Further Reading:

Anon. 1993. response to an inquiry re numbers of species of Unicornfish. Sea Frontiers.3,4/93.

Blasiola, George C. 1988. Description, preliminary studies and probable etiology of head and lateral line erosion (HLLE) of the palette tang, Paracanthurus hepatus (Linnaeus, 1758) and other Acanthurids. Bull. of l'Institut oceanographique, Monaco. Spec. Pub. 5:255-263.

Blasiola, George C. 1990. A review of hole in the head disease of fish. FAMA 5/90.

Burgess, Warren E. 1973. Salts from the seven seas (on the Species Z. veliferum & Z.desjardinii. TFH 5/73.

Burgess, Warren E. 1977. The chevron tang. TFH 3/77.

Burgess, Warren E. 1979. The genus Zebrasoma. TFH 11/79.

Burgess, Warren E., Herbert R. Axelrod & Raymond E. Hunziker III.1990. Atlas of Aquarium Fishes Reference Book, v. 1 Marine Fishes. T.F.H. Publications, NJ. 768pp.

Campbell, Douglas G. 1979. Fishes for the beginner, A guide for the new marine hobbyist, Parts three and four, Tangs. FAMA 1,2/79.

Chlupaty, Peter. 1979. Keeping the yellow tang. T.F.H. 7/89.

Collins, Steve. 1995. Dietary control of HLLE in blue tangs. SeaScope Summer 95.

Debelius, H. 1975? Useful information on Surgeonfish. Aquarium digest Intl. #29, pp 31-33., #31, pp 28-29.

Debelius, Helmut. 1993. Indian Ocean Tropical Fish Guide. Aquaprint Verlags, Germany.

Debelius, Helmut & Hans A. Baensch. 1994. Marine Atlas. Mergus, Germany. 1,215 pp.

Emmens, C.W. 1985. Surgeonfishes. TFH 1/85.

Fenner, Robert. 1996. Will the real powder brown tang please swim up? TFH 3/96.

Fenner, Robert. 1997. Unicorn tangs, genus Naso, family Acanthuridae. SeaScope v.14, Spring, 1997.

Fenner, Robert. 1998. The Conscientious Marine Aquarist. Microcosm, VT. 432pp.

Hoover, John P. 1993. Hawai'is Fishes: A Guide for Snorkelers, Divers and Aquarists. Mutual Publishing. Honolulu, HI.183pp.

Jones, Lawrence L.C. 1988. Care and maintenance of tangs in captivity. Part one: Food and feeding. FAMA 10/88. Part II. Behavior, FAMA 3/84.

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.

Lobel, Phillip S. 1984. The Hawaiian Chevron Tang, Ctenochaetus hawaiiensis. FAMA 3/84.

Madsen, Pieter. 2000. A tang by any other name... TFH 6/00

Maisey, John G. 1996. Fossil surgeonfishes. TFH 4/96.

Meyer, K.D., Paul, V.J., Sanger, H.R. and S.G. Nelson. 1994. Effects of seaweed extracts and secondary metabolites on feeding by the herbivorous surgeonfish Naso lituratus. Coral Reefs 13(2):105-112.

Michael, Scott 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.

Michael, Scott W. 1998. Surgeonfishes; Meet their strict care requirements, or else... AFM 9/98.

Michael, Scott W. 1998. The surgeonfishes. Getting to the point- the species. AFM 10/98.

Nelson, Joseph S. 1994. Fishes of the World. 3rd Ed. Wiley. 600pp.

Nelson, S.G. & Y.M. Chiang. 1993. An exploratory analysis of the food habits of herbivorous surgeonfishes (Acanthuridae) from French Polynesia. Proceedings of the Seventh Intl. Coral Reef Symposium, v. 2:920-926. Univ. of Guam Press. Polunin, N.V.C.,

Harmelin-Vivien, M. & R. Galzin. 1995. Contrasts in algal food processing among five herbivorous coral-reef fishes. J. of Fish Biology 47(1995):455-465.

Randall, J.E. 1955. A revision of the surgeonfish genus Ctenochaetus, Family Acanthuridae, with descriptions of five new species. Zoologica 40:149-165.

Randall, J.E. 1955. A revision of the surgeonfish genera Zebrasoma and Paracanthurus. Pac. Sci. 9:396-412.

Randall, J.E. 1956 A revision of the surgeon fishes genus Acanthurus. Pac.Sci. 10:159-235.

Randall, J.E. 1975 Hawaiian fish profiles. ADI 3:2, pp 12,13.

Randall, J.E. 1986. Acanthuridae; in Smith's Sea Fishes. Springer-Verlag, Germany. pp. 811-823.

Randall, J. 1988. Three nomenclatorial changes in Indo-Pacific surgeonfishes (Acanthurinae). Pacific Science 41:54-61.

Randall, John E. 1996. Shore Fishes of Hawai'i. Natural World Press, OR USA. 216pp.

Ranta, Jeffrey A. 1996. Dealing with HLLS. TFH 1/96.

Sands, David. 1994. Superb surgeons. FAMA 10/94.

Spencer, Gary C. 1973. The tang and I. Marine Aquarist 4(4):73

Stratton, Richard F. 1989. The achilles tang. TFH 1/89.

Surgeonfishes: Tangs for Marine Aquariums
Diversity, Selection & Care
New eBook on Amazon: Available here
New Print Book on Create Space: Available here
by Robert (Bob) Fenner

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