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 surgeonfishes' 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):
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.
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.
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:
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.
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 peduncular-spined fishes. Their "tangs" are movable; and yes, they know how to use them.
Species on Review:
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.
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.)
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