Northern wolffish, Anarhichas denticulatus.
Northern Wolffish, Anarhichas denticulatus

The northern wolffish has a thickset body that resembles a fat, stumpy eel. However, unlike eels, the wolffish has a well developed and separate caudal fin. The dorsal fin is of a uniform width from the top of the head to the base of the caudal fin, and the anal fin, which begins approximately halfway along the body, also ends at the base of the caudal fin. In order to differentiate the northern wolffish from the other three species, colouration is important; the body of the northern wolffish has very little marking and is a uniform deep brown as opposed to the others, which are striped or spotted. The northern wolffish can grow to a very large size, with the average adult measuring 1.3 m in length and weighing up to 20 kg.

This fish is found in the arctic waters of both North America and Asia, and has also been caught off Greenland and Iceland. Due to its large size and broad distribution, it is a commercially important fish and contributes substantial poundage to catches. However, there has been little study of its ecology or life history.