Description
The butterfish or gunnel has an elongated, laterally compressed body. Highly distinguishable by the 12 dark brown to black spots, with a white or yellow outline all along the dorsal fin. The dorsal fin and the anal fin both run to the tail fin. The pelvic fins are very small and have more the shape of a spine. The common name origins from the greasy skin. Spawning time is end of the winter when the eggs are deposited between rocks and shells, in small lumps of several hundreds. Both partners guard the eggs until the larvae hatch after a month. They feed on small polychaetes worms, crustaceans and molluscs.

Size
Length up to 250 mm.

Colour
Main colour is brown to reddish brown, with an irregular pattern of darker patches on the sides and a dark line across the eye. In mating season the male will show bright yellow pectoral fins and breast.

Habitat
Shallow sub tidally, on hard substrata.

Distribution
North Atlantic from Labrador to Delaware and from Iceland to the Bay of Biscay.