There are many different species of blennies. They are small fish covered in slime rather than scales. They can have a crest and their eyes are towards the top of their large head. They are usually found hiding at the bottom of the intertidal zone in a rockpool, rock platform, under loose rocks, sand, mangroves or on mud. A pair may hide in a large shell or even in a bottle.
They are less likely to take off when there is danger compared to other fish and will only move out of your way. The many different species eat different kinds of food. They could be eating algae or a wide range of tiny sea creatures. Blennies can be eaten by larger fish and by the many birds that feed in the intertidal zone.