Paracanthurus hepatus is a
species of Indo-Pacific surgeonfish. A popular fish in marine aquaria, it is
the only member of the genus Paracanthurus. A number of common names are
attributed to the species, including regal tang, palette surgeonfish, blue tang
(leading to confusion with the Atlantic Acanthurus coeruleus), royal blue tang,
hippo tang, flagtail surgeonfish, Pacific regal blue tang and blue surgeonfish.
Paracanthurus hepatus has a royal blue body, yellow tail,
and black 'palette' design. The lower body is yellow in the west-central Indian
Ocean. It grows to 30 cm (12 in.). This fish is rather flat, like a pancake,
with a circular body shape, a pointed snout-like nose, and small scales. The
blue tang has 9 dorsal spines, 26–28 dorsal soft rays, 3 anal spines, and 24–26
anal soft rays.