Red Sea Surgeonfish

Acanthurus gahhm, commonly known as the black surgeonfish, monk surgeonfish, or lined surgeonfish, is a marine ray-finned fish species within the family Acanthuridae, which encompasses surgeonfishes, unicornfishes, and tangs. This species is geographically located in the undefined.

First formally described by the German naturalist Johann Friedrich Gmelin in 1789, Acanthurus gahhm's type locality is presumed to be the 🌊 Red Sea, although it was not explicitly specified. The genus Acanthurus constitutes one of two genera within the tribe Acanthurini, part of the subfamily Acanthurinae, which belongs to the larger family of Acanthuridae.

The specific epithet "gahhm" is derived from an Arabic term for surgeonfish in the 🌊 Red Sea region, initially noted by Peter Forsskål in 1755 as a common name, and later validated as a scientific name by Gmelin in 1789.

Acanthurus gahhm grows to a length of up to 50 centimeters. It features an oval, laterally compressed body characteristic of surgeonfishes, with locomotion primarily facilitated by its pectoral fins. The caudal fin displays a crescent shape, and the fish is distinguished by a small, pointed mouth. Its body coloration ranges from black to dark brown, accented by a white ring around the tail base and a yellow stripe encircling the eyes. Yellow-tipped pectoral fins complete its distinct appearance.

The distribution of Acanthurus gahhm is confined to the north-undefined, with its presence endemic to the 🌊 Red Sea and the 🌊 Gulf of Aden. Reports of this species further east are likely misidentifications of A. nigricauda.

This demersal species inhabits reef systems, lagoons, and other sandy marine environments, at depths reaching up to 40 meters. As an omnivore, it feeds on algae, zooplankton, small invertebrates, and detritus. Acanthurus gahhm is diurnal, exhibiting both social behavior by swimming in groups and solitary tendencies.