Acanthurus leucosternon is one of the 38 members belonging to the genus Acanthurus, which together with 5 additional genera make up the family of surgeonfishes (Acanthuridae) in which there are currently described a total of 73 species. It is an entopelagic species, that is to say it is a species that does not live on the bottom, but swims above the bottom, but not far from it. It lives in the crystal clear waters of coral reefs, usually at a depth of less than 25 meters. This species occurs in both the Indian Ocean and the Pacific Ocean, being present in Burma, Bangladesh, Cocos, Comoros, Cook Islands, India, Indonesia, Iran, Kenya, Madagascar, Maldives, Mauritius, Mayotte, Mozambique, Christmas Island, Oman, Reunion, Seychelles, Somalia, Sri Lanka, South Africa, Thailand, Tanzania and Yemen.
The body is laterally compressed and oval, with a small mouth that is protractile and positioned slightly lower on the snout. The dorsal fin has 9 spines and 28-30 soft rays, the anal fin has 3 spines and 23-26 soft rays, the pectoral fins have 16 rays, and the caudal fin is forked. Characteristic of this family of fish, on the caudal peduncle we find a retractable spine on each side, which it will use as a defensive method if it feels attacked.
The coloration of Acanthurus leucosternon is sky blue, with a white spot on the chest. The head is black, presenting a white stripe from the base of the pectoral fin to the throat. It has no distinctive spots or white band under the eyes. The dorsal fin is yellow, except for the white margin and the black submarginal line. The anal and pelvic fins are white. The caudal fin is white, with a band at the base and a black submarginal stripe on the outer edge.
It is common to observe specimens of Acanthurus leucosternon forming large groups of specimens to feed. It feeds on algae, of which it not only feeds on benthic algae, but also on filamentous algae on rocks. It can also feed on phytoplankton.
As for the reproduction of Acanthurus leucosternon, it is a species that forms stable couples, which release the gametes into the water column so that fertilization occurs and the fertilized eggs are spread by the currents.
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