Okay, it’s not
the most exciting and colorful of marine fish, but the scopas tang (Zebrasoma
scopas) is a utilitarian fish and a staple in the marine aquarium
hobby.Lately, I’ve
become somewhat fascinated with this fish.I’ll get to that later.
The
scopas tang, or brown tang, is a member of the genus Zebrasoma,
which is a part of the family of tangs and surgeonfish,
Acanthuridae.The genus Zebrasoma
is a relatively small genus consisting of seven species that are
characterized by their round, laterally compressed bodies and
pointed snouts.They’re popular in the aquarium trade because of
their color, shape, and propensity to eat nuisance algae in the
aquarium.The long snout enables Zebrasoma tangs to reach filamentous algae in reef interstices that
are out of the reach of other Acanthurids.Zebrasoma are
found in every tropical ocean and sea except the Atlantic.The scopas tang is equally widespread and occurs throughout
the Indo-Pacific Ocean from Africa to Japan.Juvenile scopas tangs are generally solitary fish and never
stray far from the cover of the reef.Adults roam wide expanses of the reef and can be found
singly, in pairs and in large groups of the same or mixed species
of tangs.They inhabit lagoonal areas as well as the outer reef from
a depth of two to sixty feet.There are no visible differences between males and females
of the species, but juvenile scopas tangs have exaggerated dorsal
and anal fins as well as thin white vertical lines that transverse
the body.In some respects they resemble juveniles of the sail fin
tangs, Z. desjadinii and
Z. veliferum.Scopas tangs reach an ultimate adult size of 20 cm.That’s quite a bit smaller than the giants of the genus,
the sailfin tangs, which can reach lengths of 30-40 cm.
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Black-colored
scopas tangs (Zebrasoma scopas) are sometimes sold as “black tangs” (Zebrasoma
rostratum).Pictured is the genuine “black tang.”Note the greenish tinge that runs along the dorsal
spine.This is absent in scopas tangs.
The
coloration of scopas tangs is highly variable.It incorporates shades of gray, brown, yellow and white.Some specimens can be solid yellow, while others solid
black!The black variants are sometimes sold as Z.
rostratum, the black tang.The genuine black tang is a more expensive fish with
limited distribution.It differs from the scopas in having a longer snout and a
greenish tinge that runs along the base of the dorsal fin.There are reports of interspecific hybridization, which may
explain the appearance of black scopas tangs. There are also odd
scopas tangs that appear to be a mix of black, yellow (Z.
flavescens), and brown tangs.There’s some question as to whether these wild color
schemes are the result of cross-breeding or simply mutations.There’s even speculation that it’s related to a fungus!I can attest to the fact that these “mutant” scopas
tangs will and often do change color in captivity, so be careful
what you pay for!I have a specimen that changed from a mostly yellow
coloration, with splatterings of black, into one that’s now half
brown and yellow.This color change occurred over a period of a few months.
Scopas
tangs mate in groups by scattering eggs and sperm into the water
column.It’s
unlikely that they will reproduce in home aquariums, although the
spawning behavior of the similar yellow tang has been observed in
captivity at the Waikiki Aquarium.
The
scopas tang is not a demanding fish in captivity.It does best in a larger aquarium, which satisfies its need
to roam and imparts a sense of security.Zebrasoma tangs in general tend to be more skittish in smaller
aquariums.I
wouldn’t keep a juvenile in anything smaller than a thirty-long.A reef-type aquarium is the best setup for a scopas tang.They benefit from the bright light, improved water quality
and additional feeding opportunities afforded by a reef aquarium.They’re also less-likely to develop head and later line
erosion (HLLE) in reef setups.This disfiguring malady is thought to be related to
deteriorating water quality, nutritional deficiencies and dim
lighting.Zebrasoma tangs are particularly susceptible to it.
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Zebrasoma
tangs often suffer the symptoms of head and lateral line
erosion (HLLE) if they are not provided with adequate
nourishment and appropriate aquarium conditions.Tangs maintained in reef aquariums rarely suffer from
this malady.The purple tang (Zebrasoma
xanthurum) in this picture was returned to a retail store
by an ill-informed aquarist.
The
scopas tang is predominantly herbivorous, but will eat a variety
of foods in captivity.They’re not finicky eaters and, if otherwise healthy,
will adapt quickly to prepared foods such as spriulina-enriched
flakes, dried macro-algae, mysis and brine shrimp, and other meaty
seafoods.They have a high metabolism, especially juveniles, and will
lose body weight quickly if not fed at least daily.I recommend feeding dried macroalage in clips, or
rubber-banded to rocks, at least every other day. Ocean
Nutrition’s Seaweed Selects and Two Little Fishies’ Sea
Veggies offer a variety of dried macroalage products.Well-fed scopas tangs are also less likely to pick on
sessile invertebrates.While Zebrasoma
tangs are generally considered “reef-safe,” individuals have
been known to occasionally pick at large-polyped stony corals and
soft corals.Offering alternative feeding opportunities, such as algae
in a clip, will sometimes thwart this bad behavior.Many Zebrasoma
tangs will pick at the “mouth” of large-polyped stony corals
to induce the release of excess zooxanthellae, which the fish
relish.This generally does no harm to the coral.
When
purchasing a scopas tang look for an alert individual that is
actively grazing around the aquarium.Ask to see the fish eat.There’s something wrong with a scopas tang that won’t
eat.Avoid fish that exhibit “flashing” behavior.This is where the fish acts agitated, spreads its fins and
dashes across the aquarium.Also avoid fish scraping against the rocks, with obvious
signs of external parasites, or with patchy white areas on any of
the clear fins.Torn fins are okay and will heal quickly.They’re usually the result of battles with other tangs.Scopas tangs use their sharp “scalpels,” which are
tucked into sheaths on their caudal peduncles, to slash at rival
tangs.
This healthy and vibrant purple
tang (Zebrasoma xanthurum) has been a resident in one of the author’s
reef aquariums for 7 years.It would be difficult to mix this fish and the scopas
tang (Zebrasoma scopas) in the same aquarium because they share a
belligerent disposition.
Pictured is the yellow tang (Zebrasoma flavescens), which is very similar to the scopas tang (Zebrasoma
scopas) but currently a distinct species.
Scopas tangs are often
underfed at retail establishments and begin to show signs of
starvation.If the
starvation has progressed to the point where “pinching” can be
observed in the area of the dorsal musculature (the muscles
running along the top of the spine, below the dorsal fin), then
the fish will usually not recover.“Pinched” stomachs are common and the fish can be
fattened up quickly by allowing it to graze continually on dried
macroalage for a few straight days.
The
author’s scopas tang (Zebrasoma scopas) shares a 40 gallon reef aquarium with 6 pajama
cardinalfish (Sphaeramia
nematoptera) and various hard and soft corals.Lighting is provided by a single 150 watt HQI fixture
(Iwasaki 50K bulb) driven by an Ice Cap electronic ballast.
This
is the same scopas tang (Zebrasoma scopas) pictured previously.After a few months in captivity, the coloration changed
dramatically to half brown and yellow.It’s maintained the white tail fin though.The fish is thriving in a 40 gallon reef aquarium.
This
scopas tang (Zebrasoma
scopas) was nearly all yellow in color when first acquired
by the author.Note
the white tail fin, which is also unusual for this species.
This
is the typical coloration and appearance of the scopas or brown
tang (Zebrasoma scopas).This is a healthy specimen in the author’s reef
aquarium.
Scopas tangs, like most of
the Acanthurids, are susceptible to parasites.They benefit from a period of quarantine, where they can be
treated medicinally, if necessary, and learn to accept prepared
foods.They can
recover spontaneously from parasitic infections, if the display
aquarium offers a stress-free environment and they are well-fed,
but quarantining is always best.
Scopas tangs are
territorial fish that can be belligerent towards other fish,
especially those from the same genus.I would not mix more than one scopas tang in anything but
the largest of aquariums.You’ll
also find it difficult to mix other Zebrasoma tangs in the same aquarium with a resident scopas tang.The best chance is to mix large and small specimens of
different Zebrasoma
species, with the larger specimen preferably introduced last.
Zebrasoma
tangs will sometimes pick at the mouths of large-polyped stony
corals to induce the release of excess zooxanthellae.This generally does no permanent harm to the coral.Pictured is a yellow tang (Z.
flavescens) “picking” at a Cynarina
coral.
