Found off most UK coasts where there is weed cover, the Sea Stickleback, Spinachia spinachia, is unlikely to be confused with any other fish. However, it is very hard to spot due to its habit of hanging motionless in the kelp. Up to 25cms long, it can be found in rock pools and to a depth of about 20m. They are nest builders and the female dies after laying her eggs with the male tending the nest until hatching takes place.
Also called the Fifteen-spined Stickleback.