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
Here is my account of
handling the Zebrasoma, who they are, how to pick out worthy
specimens, and maintain them.
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
(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
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
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
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
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,
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
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
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
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
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
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.
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
the permission of Robert (Bob) Fenner webmaster