This Northern Clingfish had locked itself between the arms of an Ochre Starfish (Pisaster ochraceus). They use their pelvic fins to create a strong suction action that holds them fast to rocks, even in rushing water.
Clingfishes are fishes of the family Gobiesocidae, belonging to the order Gobiesociformes. Most species are marine, being found in shallow waters of the Atlantic, Pacific and Indian Oceans. They are bottom-dwelling fishes; some species shelter in sea urchins or crinoids.