Centrolophus

The black ruff (Centrolophus niger) is a medusafish, the only member of the genus Centrolophus. It is a mesopelagic fish found in all tropical and temperate oceans at depths of 50 to 1,000 m. Its length is typically up to 60 cm, but it may reach 150 cm. Other common names include rudderfish and blackfish.