Length up to 16 cm.
Also called the Common Blenny or Smooth Blenny, the colouration of this fish is variable, from dark brown to greenish depending on its surrounding environment.
With no scales it is covered in a protective slime which stops it from drying out during periods when it is out of the water. It has an elongated body with a long single dorsal fin. It has sharp teeth and can bite humans if handled incorrectly.
The males guard the eggs until they hatch. It feeds on small invertebrates, including the Acorn Barnacle (Semibalanus balanoides). It can live for up to 15 years.
Found in pools, amongst seaweed and under rocks on the lower shore. Very common around the coasts of Britain and Ireland. A native species.