Common names: tang (English), cirujano (Espanol), navajón (Espanol)
Acanthurus achilles Shaw, 1803
Body an elongate oval; head profile steep; eye high on the head; mouth small, protrusible, low on head; teeth on jaws fixed, with flattened, notched tips, 8-28 on each jaw; gill rakers 16-20; dorsal rays IX, 29-33; anal rays III, 26-29; pectoral rays 16; pelvic fin I, 5; a single depressible spine fits into a groove on the side of the base of the tail; tail fin concave; scales very small, rough; lateral line complete.
Bluish black with a large elliptical orange patch posteriorly on body; a white slash or short bar covering middle of opercular membrane; tail fin with broad orange bar and white rear margin.
Size: to 26 cm.
Habitat: shallow surge areas of rocky and coral reefs.
Depth: 0-10 m.
The tropical central Pacific; in the eastern Pacific it has been seen near Cape San Lucas (Baja California) and inside the western Gulf, and a pelagic juvenile was collected near Clipperton Island.