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Related FAQs: Chevron Tangs, Kole Tangs, Genus Ctenochaetus, Ctenochaetus Tangs 2Ctenochaetus Identification, Ctenochaetus Behavior, Ctenochaetus Compatibility, Ctenochaetus Selection, Ctenochaetus Systems, Ctenochaetus Feeding, Ctenochaetus Disease, Ctenochaetus Disease 2, Ctenochaetus Reproduction, Surgeons In General, Tang ID, Selection, Tang Behavior, Compatibility, Systems, Feeding, Disease,

Related Articles: The "Chevy" or Chevron Tang, Ctenochaetus hawaiiensis; Gorgeous and Hardy by Bob Fenner Tangs, Surgeons, Doctorfishes, family Acanthuridae, other tang genera: Acanthurus, Naso, Paracanthurus, Prionurus, Zebrasoma; Topics: Algae Control, Nutrient Control and Export

/The Diversity of Fishes Series:

The "Bristle-Tooth" Surgeonfishes, Genus Ctenochaetus

By Bob Fenner

  Ctenochaetus striatus

Surgeonfishes: Tangs for  Marine Aquariums
Diversity, Selection & Care

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by Robert (Bob) Fenner

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Marine Aquarium Algae Control

by Robert (Bob) Fenner

Tangs, Surgeons and Doctorfishes, Family Acanthuridae, are amongst the most commonly kept marine specimens. Every Aquarist "worth their salt" can identify a Naso, Yellow, Hippo/Palette/Yellow-Tail Blue Tang. Surgeonfish use in our hobby is well warranted; their numerous and easy to catch on the worlds tropical reefs, and several species in the family live comfortably under captive conditions.

Well, one might ask, "What about the others; what's wrong with them?" An answer might involve the fact that some in the genera Naso, Prionurus, just get too darn big, requiring aquariums of hundreds to thousands of gallons at adult size. Other reasons abound for the unsuitability of additional species, and reciprocally, a lot of Acanthurids are too drab to be of interest to saltwater aquarists. But what of the topic of this piece, the surgeons of the genus Ctenochaetus ("ten-oh-key-tus")?

They're attractively shaped, colorfully marked, and interesting behaviorally... why 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 avoidable reasons this is so (capture, handling, transport, and feeding) I will lay out here, and offer suggestions to improve their longevity.

Classification: Taxonomy, Relation with Other Groups

One of six genera of Acanthurids, Ctenochaetus comprises nine of the seventy-five or so described species of Surgeonfishes. Specialized mouths and teeth (cteno-chaetus means "comb bristle" define the genus' members. Unlike other surgeons that have rigid, attached dentition, Ctenochaetus have movable, individual, bristle-like teeth. Coupled with a protrusible, outreaching mouth, these fishes use this unusual feeding device to sort and remove interstitial fauna, scrape soft algae, and "detritus" of nutritive value from rock and substrate.

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

Ctenochaetus binotatus Randall 1955, the Blue-Eye or Two-Spot Bristletooth for the two dark areas at the rear of the dorsal and anal fin bases. Sometimes brought in from the Philippines. Below: A juvenile in Mabul, Malaysia and adult pix in Gili Air, Lombok, Indonesia and Fiji.

Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

Ctenochaetus cyanocheilus Randall & Clements 2001. West Pacific; Ogasawaras through the Philippines, Indo. N. Australia and Noumea east to Samoa and Marshalls. 13.7 cm. These in N. Sulawesi. http://fishbase.sinica.edu.tw/
Summary/species Summary.php?ID=59486&genusname=
Ctenochaetus&speciesname=cyanocheilus

Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

Ctenochaetus flavicauda Fowler 1938. Central West Pacific; Line and Cook Islands, Parts of Polynesia. To about five inches in length. Peduncle and caudal fin abruptly white. This juvenile and adult photographed in the Cooks. http://fishbase.sinica.edu.tw/
Summary/species Summary.php?ID=59589&genusname=
Ctenochaetus& speciesname=flavicauda

 

Ctenochaetus hawaiiensis (Chevron Tang); All Ctenochaetus species change color with age but the chevron is most striking. Ctenochaetus 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. Below, juvenile and adult specimens in aquariums and a splendid mid-size and adult off of Kailua-Kona, Hawai'i.

Ctenochaetus marginatus (Valenciennes 1835). This Pan-Pacific (Marshalls to tropical Eastern Pacific coast) fish bears a strong resemblance to C. striatus, but may be told apart by its redder color and more square caudal fin profile. C. cyanoguttatus is a junior synonym for this species. Not commonly collected, imported. Pic from Nuka Hiva, Marquesas, Polynesia. 

Ctenochaetus striatus (Quoy & Gaimard 1828) the Striped Bristletooth, is the one member of the genus found extending into the Red Sea (but also found in the Indo-Pacific to Oceania and the I.O.); it is the most frequently imported species in Europe. It's body color is overall drab olive sporting wavy blue lines (see them in the dorsal fin?). Small orange dots are sprinkled on the head. Here are specimens in Fiji and the Red Sea and a couple tussling in the Red Sea.
Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.
Ctenochaetus strigosus Bennett 1828, the Yellow-eyed or Kole Tang; since this and the Chevron Tangs range encompass the principal islands of Hawaii they are the principal species utilized in the West. The Kole ("coal-ay") is more shallow water, surface to sixty feet or so, and the chevron is generally collected in fifty feet plus. At right: in an aquarium. Below: in Kona and Maui. Link to Bigger Pix

Ctenochaetus tominiensis Randall 1955, the Tomini Bristletooth (3), is occasionally brought in from the Philippines. Of the four regularly available species of Ctenochaetus, the Tomini Bristletooth, is the most difficult to keep. Only Ctenochaetus with angular dorsal and anal fin ends. Rarely imported. Aquarium and N. Sulawesi pix.

Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

Ctenochaetus truncatus the Indian Ocean Spotted or Goldring Bristletooth (replaced by C. strigosus in the Pac.). Overall yellow-brown to darker; with distinct pale spots, brighter anteriorly. Live just above reef in small groups/associations, mainly in Acropora fields that they dart into for safety. 5-30 m. To seven inches, 18 cm. Juveniles are bright yellow. Mauritius pic 2016.

Natural Range

Largely tropical Indo-Pacific, two species reaching north eastward to Hawaii, two to the eastern Pacific. Some to the African Ocean, one species ranges to the Red Sea.

Size:

They grow to a maximum length about six to ten inches depending on species.

Selection: General to Specific

1) Size: at purchase; small specimens, less than three inches overall length, have high mortality rates. If you're going to risk one of less dimension, I'd definitely leave it at the dealers for a couple of weeks and be assured that it was feeding before taking it home.

2) Feeding: Here we go again with this "acid test"; especially important with fishes such as the algae-scraping Bristlemouth Tangs that, once off food due to mouth or other trauma, nearly always perish. If the fish is not eating, wait till it does to buy it. At right, a Yellow Eye, Kole Tang (C. strigosus) with a bad mouth: doomed.

3) Behavior: the element of "brightness", curiosity in the environment, normal swimming and evasiveness cannot be discounted. Buy well-adjusted specimens.

Environmental: Conditions

Habitat

These fishes, though slow moving, shy and retiring, require large amounts of tank space to be truly happy. Additionally, that space should have a propitious amount of hollows and surface area, for hiding and foraging.

A fine gravel bottom and lots of calcium carbonate based rock will go a long way in providing diatom growth, other detritus for inorganic and organic nutrition.

Chemical/Physical

Bristletooth Tangs live in the brisk current environments of steep reef faces. As such they are accustomed to being buffeted by waters that are high in oxygen and low in soluble wastes. These parameters may be matched in pursuing one of two strategies: either super-fastidious filtration and control, or live-algae, low stocking-rate. The latter is my choice.

Through less than tidy housekeeping and culturing live rock growth, a good deal of nutrient is reconstituted as food and readily removed by Ctenochaetus. This is one situation where you should avoid vacuuming the gravel of the system; instead allowing the livestock to circulate loose matter around.

Higher pH's are called for (8.0 and 8.4.), and temperature for all species in the seventies degrees Fahrenheit.

Filtration

As stated emphatically elsewhere these surgeons are openly detritivorous, deriving biological and mineral material from scrounging around rock and sediment. Hence, it is important to not be meticulous in removing such material.

Rigorous circulation is appreciated, from power-heads or other fluid-moving pump(s). Lighting that favors algae growth as well.

Behavior: Territoriality

Though Ctenochaetus are generally easy going with other fishes, (including different genera of surgeons stipulated that they are of widely different size), they can be, or become sheer terrors with members of their own kind or tankmates. Even though often found in pairs or even schools in the wild, they are best kept one to a tank unless the system is HUGE.

Small Ctenochaetus are highly regarded for use in "reef" systems. They make for well-adapted additions will not attack invertebrates that are useful for algal control.

A comment re that so tang-like defensive mechanism, in Ctenochaetus a single peduncle spine; these are potentially lethal weapons, able to render a sharp laceration to tankmates and unwary aquarists. Don't be fooled by these fishes' casual movements and smallish size; they are capable of doing serious damage. Want more? There are accounts of acute pain and swelling from puncture wounds caused by Ctenochaetus dorsal and anal fin spines. Keep your eyes on your other livestock, and hands if/when in the tank.

Introduction/Acclimation

The vast percentage of members of this surgeon genus is lost through rough handling and transport. You must take great pains to ensure that the fish you buy are not net and/or bag damaged, and consequently protected from such.

Professional collectors recognize the dangers in thrashing Bristlemouth tangs in coarse, rough hand and barrier nets. They should be as sensitive to the dangers of miss-shipping them as well. If at all possible, avoid netting these fishes altogether, instead drive them into submersed bags, not hard specimen containers. Further eliminate the possibility of damaging their protruding mouths by using bag sizes and water volumes sufficient for turning.

Per the comments offered on habitat and feeding, your Ctenochaetus should be placed as the last of fishes to the system.

Predator/Prey Relations

Large predaceous reef fishes like basses, eels, and etc prey upon surgeons. Keep them separately.

Reproduction, Sexual Differentiation:

Debelius (in ADI) gives some observations on spawning of C. striatus. In a group, some individuals changed from dark brown to light beige. Becoming more active, three to five would dart to the just under the surface, releasing their gametes. Debelius and Baensch (1994) state that C. strigosus spawns only in pairs.

The sexes are indistinguishable externally.

Feeding/Foods/Nutrition: Types, Frequency, Amount, Wastes

Due to mouth traumas and typical non-feeding for several days covering capture, initial holding, shipping and probable wholesale redistribution, getting Ctenochaetus (as well as all marines) to feed in short order should be a top priority.

Maybe a better name than "hairy" is "comb" bristles in reference to Ctenochaetus teeth. It occurs to me that this is more descriptive of these fishes feeding habits; their sucker-like mouths and movable teeth sift and lift loose materials. They do not nip off hard, large foodstuffs like other tangs.

My favorite "gimmick" with these fishes is to utilize an algal covered "feeding stone" as a site for engendering food-taking behavior. I encourage you to do the same; placing (I use a big "turkey" baster) waterlogged dried, fresh, and/or defrosted frozen food as fine material amongst the algae.

For surgeons, the "hairy toothed" tangs benefit from much more than a diet heavy in greens does. A high protein (forty percent plus), even purposely vitamin enriched diet shows in well-fleshed and colored specimens.

As stated elsewhere, these fishes are grazers that do well only in under crowded, less-than tidy tanks, with plenty of rock and detritus to pick over. Randall (1955) recorded up to 90% inorganic sediment in analysis of gut content of C. strigosus from the wild.

Disease:

Ctenochaetus tangs tend to arrive in "clean" condition. Though other authors endorse copper medications with them, I would rather urge you to use freshwater dips and quarantine for the two-pronged benefits of eliminating infestation and hardening your new specimens.

Close:

The dismal survival rates for Ctenochaetus are more a function of poor capture, handling, transport and feeding problems imposed by their captors, than these fishes suitability as captive specimens. Given attention to preventing damage to their sensitive mouths, a not too fastidiously clean environment, and provision of adequate foodstuffs "hairy toothed" Surgeonfishes make beautiful, long-lasting aquarium additions.

Bibliography/Further Reading:

New Print and eBook on Amazon

Marine Aquarium Algae Control

by Robert (Bob) Fenner

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

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.

Debelius, Helmut. Undated. Interesting information about surgeon (sic) fisch- III The Ctenochaetus genus. Aquarium Digest International #31.

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

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

Fouda, M.M. El Sayed, A.A. & Z.T. Zaki. 1988. Reproductive biology of a Red Sea Surgeonfish, C. striatus (Quoy & Gaimard, 1824). Proceedings of the Sixth Intl. Coral Reef Symposium. Vol. 2 pp. 679-683.

Guiasu, Radu C. & Richard Winterbottom. 1993. Osteological evidence for the phylogeny of recent genera of surgeonfishes (Percomorpha, Acanthuridae). Copeia 1993(2):300-312.

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

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

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

Nelson, S.G. & S.D. Wilkins. 1988. Sediment processing by the surgeonfish C. striatus at Moorea, French Polynesia. J. of Fish Biology 32(6) 1988:817-824.

Purcell, S.W. & D.R. Bellwood. 1993. A functional analysis of food procurement in two surgeonfish species, Acanthurus nigrofuscus & C. striatus (Acanthuridae). Env. Biol. of Fishes 37(2) 1993:139-159.

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

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

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

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

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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