Scientific name: Cottus gobio
Nature Stars: 60
About: A small fish, 10-18cm long. A strangely shaped fish, with a very large head, relatively large fins and tapering body. Lives on the bottom of fast, stony rivers and streams. Feeds on invertebrates such as mayfly and caddis fly larvae and eggs of other fish.
How to identify: Found by turning stones, unlikely to be mistaken for any other fish.
Where: Found in England and Wales, absent from Scotland.
Fantastic fact: Bullheads are nocturnal, spending their days hiding under stones.
Photograph credit: Michel Roggo/naturepl