The Best Tang (for
large, rough and tumble systems) In The World?
What? "Is he joking?" "Everyone knows the
yellow tang, Zebrasoma flavescens is the most popular,
hardiest member of the Doctorfish family." Well, the yellow is a
tough customer if collected and housed correctly. But I assure
you that it has nothing over the Sohal, Zebra, or Red Sea Clown
Surgeon, Acanthurus sohal.
This fish has much going for it; good looks,
ready food acceptance, disease resistance, active, interesting
behavior. The only negative I would have applied to it in years
past is "expense"; but no longer. Sohal tangs are Red Sea
endemics, only found in that magical area; and their cost has
come down with the recent growth in exports from the area.
Acanthurus sohal is still not cheap, but
well worth the investment in terms of beauty and longevity.
Classification: Taxonomy, Relation
With Other Groups
Surgeonfishes are part of a loose assemblage in the largest
Order of fishes, the Perciformes, in the Sub-order Acanthuroidea.
Related families include the Siganidae (Rabbitfishes like the
Foxface, Lo vulpinis), scats (Scatophagidae), and Moorish
Idol (family Zanclidae) among others. Think about the traits
these families members have in common. Bodies that are deeply
laterally compressed; small mouths; relatively large swim
bladders; with elongate nasal bones that give a high-headed
appearance. They all have a single dorsal fin with spines and
soft rays; smallish gill openings; lunate caudal fins; 22 or 23
The surgeonfish family, Acanthuridae and its
seventy-two species should be familiar to you; several members
are used for marine aquariums and food fishes. Also called,
Doctorfish, and Tangs these bony fishes are distinguished by
their elaborate spine-locking mechanism (a recessed groove for
the first dorsal and anal fin support), and the knife-like
projections (Acanthus is Greek for "thorn") they bear on their
All tangs are principally herbivorous,
feeding mostly on algae. Another salient characteristic is their
passing through a bizarre transparent larval stage termed the
There are six genera of surgeons; Naso,
Paracanthurus, Prionurus, Zebrasoma,
Ctenochaetus and Acanthurus. Some other members of
the genus Acanthurus ("Ah-Kan-Thur-Us") you've probably
Acanthurus achilles (Achilles tang)
Acanthurus coeruleus (the Atlantic blue
Acanthurus glaucopareius (Powder brown or
Acanthurus japonicus (Gold-rimmed
Acanthurus leucosternon (Powder blue
Acanthurus lineatus (Clown surgeon)
Acanthurus olivaceus (Orange shoulder
Acanthurus triostegus (Convict tang)
Surgeons are entirely marine. They are found
in all tropical seas, mostly as pelagic reef fishes, though some
are oceanic. Acanthurus sohal is confined to the Red Sea.
Though some open-ocean surgeons approach two
feet in length, the Sohal generally max's out at about eight
inches in captivity.
Selection: General to Specific
I generally urge folks to consider four
criteria separately and together when judging the acquisition of
acanthurids: body conformation, color, behavior, and time in
captivity. For the sohal tang, this is almost always
superfluous. I have rarely seen a defective imported specimen.
Depending on how long your dealer has had the
sohal in their care it might have "thinned" out. If not too
pinched in and still eating (ask for a demonstration); the fish
should revive and quickly fill out.
Of course you should be on the look out for
usual disqualifiers; cuts, sores, obvious poor care... but
outside these human-caused problems, this species is
exceptionally tough and consistently of high initial quality.
Sohals live close to reefs and the
open edge of same. They appreciate broken physical environments
with rock, coral skeletons to pick over, and plenty of open
space to swim about. Like the other members of its genus, this
Acanthurus is a fast moving, active swimmer that needs
room to move.
As with other Red Sea livestock, sohal tangs
need consistent, high quality water. The salinity should be kept
near 1.025 and constant; pH should be buffered between 8.2 and
8.4., and temperature in the mid seventies to low eighties
Sohals are big-eaters and defecators; their
system should be vigorously circulated, aerated and filtered. Do
you think a redundant power-head, outside water pump, bubbler
would be a good idea? Me too.
Some tang species are prime candidates for a
degenerative condition called "head and lateral line erosion" (HLLE),
a pitting of the pores of the lateralis system. Various theories
point to stray voltage, nutritional deficiencies, bacterial,
Protozoal involvement... and "water quality" as root causes
alone, or in concert. Whatever the sources, for the latter
concern, a maximum measurable nitrate level of 25ppm kept in
line via filtration and water changes is suggested.
As with most members of its genus, the Sohal
is best kept "celibitaire", one to a tank. Acanthurus
tangs can get into nasty scruffs with other fishes, but "to the
death" ones with conspecifics and ones that look too much like
As for placing sohal tangs in "reef" systems,
I've seen them used as such, and read of others experiences
through the electronic bulletin boards. This species, when
gotten small (3-4") typically leaves invertebrates alone and is
useful for algae control.
Unless you have a system of hundreds of
gallons you should stick with one Sohal. Other species in the
genus Acanthurus should be avoided or chosen and
introduced with extreme care. Pay special attention to
introducing fishes of decidedly different size and place the
smaller individuals first. Other less dominant fishes in the
system should be afforded as much hiding space and crevices as
Sohals, like all tangs, tend to get damaged,
even tossed out on to the floor during handling. Try to avoid
netting them altogether by directing specimens into open
doubled-bags or specimen containers underwater. Watch your
hands at all times around Surgeonfishes; their fin spines
and "thorns" are painfully sharp, and they know how to use them;
against tankmates, and humans.
I have yet to see or hear of a sohal tang
attacked by a tankmate, or challenged on the reef by other than
other Acanthurus; and then only till one retreated.
Reproduction, Sexual Differentiation:
Not successfully spawned and reared in
captivity as yet. There are no definitive color or structural
differences between the sexes. The Sohal probably spawns as
other tangs, congregating in pairs tied to lunar cycles,
releasing floating gametes to their surface fates.
Sohal tangs are perhaps the most omnivorous
of Surgeonfishes. They do need their daily greens, but accept
greedily all other forms of foods, meaty and non.
Please do not rely solely on terrestrial
lettuces for your tangs green-needs. Oriental store algae, live
rock and algal sources, specialty flakes and more are better
sources of nutrition.
Food should be offered often in small
amounts; ideally through the use of an automatic feeder, stocked
with an appropriate mix of prepared foods, set to a maximum
number of feedings. When awake, surgeons are constantly on the
prowl for edibles.
Disease: Infectious, Parasitic,
Nutritional, Genetic, Social
Some other writers have marked Acanthurus
sohal as being particularly susceptible to marine ich (Cryptocaryoniasis);
I have not found this to be the case. Such instances of
Protozoal or bacterial infection should be dealt with by
avoidance; quarantine and dipping. A word of caution re tangs;
constant treatment with captive "remedies" like copper has
proven to be counterproductive; as essential gut-fauna are
attacked as well.
Don't be dissuaded (out of hand) by the price
of Red Sea specimens for your marine system. Most are well worth
the extra cost. The Sohal tang is one prime example. Almost all
imported specimens thrive; and they're gorgeous. The best of
their family? You must decide for yourself.
Campbell, Douglas G. 1979. Fishes for the
beginner, A guide for the new marine hobbyist, Parts three and
four, Tangs. FAMA 1,2/79
Colin, P.L.; Clavijo I.E. 1988. Spawning
activity of fishes producing pelagic eggs on a shelf edge coral
reef, southwestern Puerto Rico. Bull. Mar. Sci. vol. 43, no. 2,
Debelius, H. 1975? Useful information on
surgeon fish. Aquarium digest Intl. #29, pp 31-33., #31, pp
Fenner, Robert. 1996. Will the real powder
brown tang please swim up? TFH 3/96.
Fenner, Robert. 1998. The Conscientious
Marine Aquarist. Microcosm, VT. 432pp.
Fishelson, L., Montgomery, W.L., Myrberg, A.A.
1985. A unique symbiosis in the gut of tropical herbivorous
surgeonfishes (Acanthuridae: Teleostei) from the Red Sea.
Science (Wash.) vol. 229, no. 4708, pp. 49-51; 1985.
Jones, Lawrence L.C. 1988. Care and
maintenance of tangs in captivity. Part one: Food and feeding.
Maisey, John G. 1996. Fossil surgeonfishes.
Nelson, Joseph S. 1984. Fishes of the World.
2nd Ed. Wiley.
Sands, David. 1994. Superb surgeons. FAMA