Viviparous blenny

The viviparous eelpout has a slim, tapering body and resembles a small burbot (Lota lota), a wide head and mouth and protuberant lips. It has long, ribbon-like dorsal and anal fins which continue on to unite with the arrowhead-shaped caudal fin. This distinguishes this fish from the two similar slim-bodied bottom-dwelling fish of the area, the rock gunnel (Pholis gunnellus) and the snake blenny (Ophidion barbatum). The bones are green. The tiny scales are embedded in the slimy skin. There dorsal fin becomes lower as it nears the caudal fin with these shorter rays being short and spinous. The colour is highly variable, although they are commonly greyish brown on the upper body and yellowish ventrally. They are marked with either a single or double series of blotches along the body and on the dorsal fin. The pectoral fins have yellow or yellowish orange edges. This species reaches a maximum published total length of 52 cm (20 in), although 30 cm (12 in) is more typical, and may weigh up to 510 g (18 oz).

The viviparous eelpoutis found in the eastern Atlantic Ocean where its range extends from the English Channel north around the British Isles, although it is absent from the Atlantic coasts of Ireland, eastwards onto the Baltic Sea and northwards through the North Sea and along the coast of Norway to the White Sea and the Barents Sea. This species occurs in the intertidal zone where it can live in marine and brackish environments, avoiding drying out when exposed at low tide by sheltering beneath rocks or in fissures in the rock or by staying submerged in rock pools. This demersal fish is normally sedentary, hiding under rocks or among seaweed. It can be found at depths between 0 and 40 m (0 and 131 ft), although it is normally found at depths of 2 to 20 m (6 ft 7 in to 65 ft 7 in).