About Acanthochromis polyacanthus (Bleeker, 1855)
Adult spiny chromis (Acanthochromis polyacanthus) can reach a maximum total length of 14 centimetres (5.5 inches). Their fins have 17 dorsal spines, 14 to 16 dorsal soft rays, 2 anal spines, and 14 to 16 anal soft rays. The front half of the body is gray, and the back half is white. The ratio of gray to white coloring varies between different reef populations, because there is little interbreeding between reefs, as this species has no pelagic larval stage. As the fish matures, its gray color can shift from blue-gray to brown. The edge of the dorsal fin along the top and the edge of the anal fin along the bottom are black. Some individuals have an overall gray body with a yellow horizontal stripe running along the midline of the body. The spiny chromis is native to the western Pacific Ocean. Its confirmed distribution includes western and central Indonesia, Papua New Guinea, northern Australia, all islands of the Philippines except Luzon, and Melanesia. This species lives primarily on coral reefs. It can be found at depths between 1 and 65 metres (3.3 to 213.3 feet), though it most commonly occurs at depths from 4 to 20 metres (13 to 66 feet).
