The black ruff has a robust fusiform body shape and can grow to a length 150 cm (60 in).

The head is grey and the body colour violet-black, dark brown or purplish, with a paler belly.

[4][5][6][7][8] It is a pelagic fish, and has been caught at a wide range of depths, from close to the ocean surface to over 1000 m.[7][8] It is largely absent from the tropics.

Black ruff is a generalist feeder, preying on any available organisms of suitable size that are present.

Prey items include small fish,crustaceans such as copepods and amphipods, squid, medusae and ctenophores.