Although a vast number of saltwater fishes flourish in Asian waters, relatively few are restricted to them, otherwise being found also in Australia, East Africa, Hawaii, and other parts of the Pacific and Indian Oceans. Found only from the island of Sulawesi and the Philippines, north to Okinawa and Southern Japan, the Powder-brown or White-faced tang is truly an Asian fish. It can be mistaken for the more widespread, but harder to keep, Gold-rimmed tang A. nigricans, which has less white on its face.
The Chocolate surgeonfish is also known as the Mimic tang because as a juvenile it is yellow or cream colored and is thought to mimic several species of pygmy angelfish. As it matures, the yellow coloration changes to become more chocolate brown. The mimicry is thought to be a protective strategy that allows the tang to feed without being attacked by damselfish competing for the same food sources. Like other species of surgeonfish, the Chocolate surgeonfish bears a sharp spine on either side of the base of its tail.