Blue Tang (lat. Acanthurus coeruleus)
A member of the surgeonfish family that has distinctive coloration
and is occasionally encountered by anglers, the blue
tang is sometimes used as an aquarium fish and is also marketed
fresh.
OTHER NAMES:
blue tang surgeon; French:
chirurgien bayolle;
Portuguese: acaraúna-azul;
Spanish: navajón azul.
The oval, deep-bodied, and compressed
blue tang is more circular than are other surgeonfish. Its coloring
is almost entirely blue, ranging from powdery to deep
purple, and it has many dark or light blue horizontal stripes
running down the sides and blending into the background.
The dorsal and the anal fins have a bright blue border, and
there is a white or yellow spine on the base of the tail. Juvenile
blue tang are colored bright yellow, whereas intermediate
fish have blue heads and bodies and yellow tails. The
yellow of the tail is the last to change to blue, and some fish
are found with yellow tails. The change from juvenile to
intermediate to adult coloration does not depend on size;
some blue adults are smaller than yellow juveniles.
Blue tang average 5 to 10 inches in length and may
grow to 15 inches long.
In the fry stage, the pelvic, the
second dorsal, and the second anal spines of some fish are
venomous and cause a painful sensation like a bee sting.
This venomous quality is lost once they reach the juvenile
stage. Blue tang form schools that may include surgeonfish
and doctorfish.
Blue tang feed entirely on
algae, mostly during the day.
In the western
Atlantic, the blue tang is
most commonly found in
Bermuda and from Florida
to the Gulf of Mexico and
Brazil. In the eastern
Atlantic, it inhabits the
waters off Ascension Island.
Blue tang favor
inshore grassy and rocky
areas and shallows above
coral reefs.