Acanthurus gahhm was first formally described in 1789 by the German naturalist Johann Friedrich Gmelin with its type locality not being given but is thought to be the Red Sea.

[6] It was thought to have been used by Peter Forsskål in 1755 but was described as an Arabic common name and not used as a valid specific name until Gmelin used it in 1789.

The body is black to dark brown, with a white ring around the base of the tail and a yellow stripe around the eyes.

[7] Acanthurus gahmm is found in the north-western Indian Ocean where it is endemic to the Red Sea and the Gulf of Aden, records farther east are likely to be misidentifications of A.

[3] This species is omnivorous, feeding on algae, zooplankton and other small invertebrates, and detritus.