Very dark brown body with blackish fins and small, firm scales that are not easily dislodged. The body is deep and angular and is dominated by a very large, green eye. A single row of four low bumps is usually present on the lower belly of juveniles, gradually disappearing when reaching maturity.

Black oreo belong to the Oreosomatidae family (oreos). They are not members of the Zeidae family (true dories) despite their market name. Black oreo are found only in the Southern Hemisphere. They are a deepwater species with a preferred depth-range of between 600 and 800 metres. In New Zealand, black oreo are found along the south Chatham Rise, off the east coast of the South Island and on the Campbell Plateau. They form schools near pinnacles and feed on crustaceans, fish and squid. Juveniles are thought to be pelagic for the first 4-5 years.   

Spawning occurs from late October to December, particularly on the south Chatham Rise. They are thought to be slow growing and to live to at least 100 years.

Spiky oreo (Neocyttus rhomboidalis) is a related species. They are paler than black oreo, have greyish fins, scales that are easily shed, a larger eye, stouter spines and a strongly concave pre-dorsal profile. They are smaller in size and are found in flatter, shallower grounds than black oreo. Spiky oreo are not as common as black oreo and are not a preferred commercial catch.