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.
Here is my account of handling the Zebrasoma, who they are, how to pick out worthy specimens, and maintain them.
Classification: Taxonomy, Relation with Other Groups
The seventy-two described species of tangs that make up the Family Acanthuridae are divided into two subfamilies, three tribes and six genera on the basis of differing numbers of spiny and soft rays in their fins, and the number and mobility of pre-caudal spines. The namesake of the family is these scalpel-like projections; "acanthus" is Greek for thorn or spine.
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.
Zebrasoma veliferum (Bloch 1795), 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.
Sailfin tangs are found on shallow reefs from the east coast of Africa northward to the Red Sea, over the broad span of the Indo-Pacific and Oceania, eastward to the Hawaiian Islands. Not found in the Atlantic or western Pacific.
Having dived with these fishes around the world’s tropical seas, I've seen how big Zebrasoma get. Think you've seen big tangs? Get out your ruler; Yellows attain eight inches, Purple and Black Longnose' over a foot, and Desjardin's fifteen inches in total length.
Selection: General to Specific
I use five criteria when judging the acquisition of Zebrasoma; body conformation, size, color, behavior, and the length of time they've been in captivity.
1) Body Conformation: Appearance of a sunken stomach is not of itself an accurate indication, but healthy, freshly collected specimens of tangs appear well rounded. The upper body, above and behind the eyes should not be "shrunk in", or show loss of color.
About the scalpel-like caudal peduncle spines or "tangs": Often enough, conscientious collectors will snip off the peduncular spines of surgeons to prevent net fouling and damage from crowding/fighting. Don't be alarmed at this; they will grow back.
2) Size Range: The minimum purchase size for the genus I peg at about three inches in length for adaptability, maximum at five.
3) Color: From studying you should know the "normal" looks of a healthy specimen. Color ought to be intense and uniform. Zebrasoma display quite different stress, fighting, nighttime markings, and often-becoming barred, blanched in color. Avoid stressed specimens, and any showing red, eroded, or blotchy markings.
4) Behavior: Sailfin tangs that have been captured, transported, acclimated and kept properly are active and curious about their environment. Avoid sulking, sedentary individuals having "private parties" at the bottom or top of their aquarium.
Is the specimen feeding? On the types of foods you'll be offering? Make sure before taking it home.
5) Time in Captivity: A good week or two should go by before taking new surgeons from your dealer. This period serves at least three critical functions; cleansing the fish of external parasites, acclimating it to aquarium conditions, testing to see if it can/will recover from capture/transport/captivity traumas.
Though Zebrasoma are somewhat smaller and less free-ranging than other acanthurid species, these tangs require large amounts of tank space to be at their best. A fifty-gallon tank is the absolute smallest I'd keep one in.
For all your livestock's sake, maximum nook and cranniness should be provided for ducking in and out of vision and harm's way. Acroporid coral skeletons are especially appreciated.
Of all the tangs, the Zebrasoma species display the most tolerance for variable water conditions. Nevertheless pH should be maintained between 8.0 and 8.4., temperature kept ideally in the mid-seventies; to low eighties F. maximum.
For cost, disease and maintenance considerations, many folks keep these fishes at low specific gravities (1.020 and even lower). This generally works out, except for the Z. xanthurum collected out of the Red Sea appreciate a higher, more constant (1.025-27) spg.
Talk about a paradox On the one hand Sailfin tangs require stable, aged systems with diatom, green algal growth and detritus... on the other, they demand low waste loads and high dissolved oxygen.
Be sure about this by providing strong water movement (four plus passes per hour) and vigorous aeration.
Sailfins are better to keep just one individual of one species to a system. They can and will fight with their species and other tangs, seriously damaging other similar appearing fishes, even in tanks of hundreds of gallons.
Should you be determined to keep more than one Zebrasoma or conspecifics together, do purchase them as a group, from the same dealer’s tank, and introduce them all at once. Per tang territoriality, these fishes should be placed last, affording their tankmates time to assert space for themselves.
I differ with other authors as to the relative fierceness of Zebrasomas with other fishes. As a group, they are the least dangerously agonistic; almost always their face-offs are more for show than go, the fish retreating or allowing retreat in systems of adequate size, uncrowded space, with plenty of cover.
But I would be remiss to not mention that, as usual, there is no substitute for careful observation. Casual, time to time "nose to tail-offs", of short duration are to be expected. Prolonged battles demand immediate separation of warring parties, or loss of at least one.
Most often utilized in "community" fish-only systems, I have seen small Sailfin tangs in reef systems to advantage. For color and algae picking Zebrasoma are hard to beat... but be forewarned; they are not above sampling non-vertebrates and can gain size surprisingly quickly; and of course will eat most algae, including Caulerpa.
These fishes, as all tangs, are best placed near last to ensure aging and stability of the system. Given plenty of room and hiding spaces your Sailfin tang should not be overly intimidated by any but the worst bully tankmates.
Though they are of spiny-fin, proficient with their razor-like peduncle scalpels, and can be ciquatoxic (poisonous for fish or human consumption), predatory fishes consume Sailfins.
Measure grouper, moray and lionfish mouths twice before introducing Zebrasoma.
Reproduction, Sexual Differentiation:
Except for Z. scopas where males noticeably change color during spawning and are quite a bit larger than females, and males of Z. rostratum which show white setae (bristles) before their peduncular spines, Zebrasoma tangs show little sexual dichromatism or dimorphism (color or structural differences between males and females).
Spawning by Zebrasoma species occurs by pairs and schools, with two or more fishes swimming rapidly toward the surface releasing their gametes. Planktonic larvae drift about via currents for weeks to a few months, with good fortune settling about a propitious reef.
Feeding/Foods/Nutrition: Types, Frequency, Amount, Wastes
Zebrasoma tangs are celebratedly herbivorous; in the wild they subsist on micro- and/or macro-algae. However, Sailfins in captivity on do best diets of meaty and vegetable materials; offered often, in small amounts.
Green foods may consist of natural algae, grown live, prepared for human consumption, or processed into flakes, pellets for pet-fish use. Some terrestrial material may make part of this mix. If utilizing broccoli, spinach, et al., do freeze or blanch it in boiling water to soften.
Many behavioral problems are prevented by having some green material available at all times; granting the fish something to nibble on other than each other. This is the primary benefit to be derived by the daily offering of virtually non-nutritive lettuce. A frozen, steamed, microwaved or boiled leaf can easily be offered on a specialty clip or banded to a rock for ready removal of the remains.
A note regarding "feeding strikes", where for no apparent reason(s), a fish will forego feeding. This happens quite a bit with Zebrasoma. If yours seems to have "given up the ghost" and stopped eating, don't you give up. Very often, just as quickly, these surgeons will resume feeding, regaining their girth. Check `your water chemistry, try a water change, an offering of a new green food... this often stirs resumption of feeding. Understand that these fishes go through periods of non-feeding naturally in the wild, storing fat in their body cavities.
Disease: Infectious, Parasitic, Nutritional, Genetic, and Social
Sailfin tangs are just as susceptible to marine ich and velvet (Amyloodinium) diseases as other surgeons; they are more responsive and less toxified by the usual remedies however. Copper compounds, dyes and formalin-formaldehyde preparations used in quarantine will assure eradication of these protozoan foes before introduction into your main display system.
A note here concerning "black spot" disease, on yellow tangs in particular. My "old" graduate school roommate, Mike Kent with the help of (Dr.) Andy Olson worked out the life cycle of this "free-living" turbellarian flatworm. This small commensal/parasite species (Paravortex), can be easily "wiped clean" off new fishes by way of a freshwater dip/bath of a few minutes duration; with or without other chemical additives.
Nutritional disorders of Sailfin tangs are so common a cause of disfigurement and loss that we'll mention them here as a disease that can be avoided and "cured". Research has shown that vitamin A & C deficiencies are a "cause" or co-cause of color loss and head and lateral-line-erosion (acronym HLLE). This pitting may be sent into remission and reversal with the feeding of these vitamins. Some aquarists utilize specific chemical food supplementation; others rely on natural or terrestrial veggie sources (broccoli, carrots...) as a source.
Close: For hardiness, adaptability, peaceful nature, acceptance of prepared foods, and beauty it's not hard, but impossible to beat the tangs of the genus Zebrasoma. All they ask for is adequate space, some algae, and decor to hide in and compatible tankmates.
With the permission of Robert (Bob) Fenner webmaster of WetWebMedia ()