Acanthurus leucosternon was first formally described in 1833 by the English naturalist Edward Turner Bennett with its type locality given as Sri Lanka.

The fish has a "surgeon's scalpel," an erected part of the spine located at the base of the tail.

[7] The mouth is small and pointed in a beak-like manner with tiny and sharp teeth for reaching narrow spaces of food.

[citation needed] The fish does not undergo color changes as it matures; as some tangs, surgeonfish and unicornfish do.

[10] The powder blue tang, like most fish in the family Acanthuridae, is herbivorous, eating mostly benthic algae.