Centrolophus

The black ruff (Centrolophus niger) is a medusafish, the only member of the genus Centrolophus. It is a pelagic fish found in all tropical and temperate oceans at depths of . Its length is typically up to , but it may reach . Other common names include rudderfish and blackfish.

==Description== The black ruff has a robust fusiform body shape and can grow to a length . The dorsal fin has five spines and 37 to 41 soft rays, the anal fin has three spines and 20 to 24 soft rays. The bases of these fins have a fleshy sheath clad with scales that partially conceals the rays. The head is grey and the body colour violet-black, dark brown or purplish, with a paler belly. The fins are darker than the body colour. Sometimes there are indistinct spots or a marbled pattern. The otoliths of black ruff are thin and delicate, and about 15 mm in length for a 40 cm fish. thumb|left|Otolith of black ruff.