Bullhead ©Jack Perks


Scientific name: Cottus gobio
Living up to its name, the bullhead has a characteristically large, flattened head and a tapering body. Look out for it in fast-flowing, stony rivers and streams.

Species information


Length: 8-12cm
Weight: 6-12g
Average Lifespan: 3-4 years

Conservation status


When to see

January to December


A small, strangely shaped fish, the bullhead (also known as the 'Miller's Thumb') has a very large head, relatively large fins and a tapering body. It lives on the bottom of fast, stony rivers and streams feeding on invertebrates, such as mayfly and caddisfly larvae, and the eggs of other fish. Spawning occurs between February and June: the eggs are laid underneath stones or in pits and the male guards and cares for them attentively.

How to identify

Found by turning over stones, the bullhead is unlikely to be mistaken for any other fish. It is brown in colour, with mottling or barring, a large head and protruding eyes. During the breeding season, the males turn black with white-tipped dorsal fins.


Mainly found in England and Wales, limited distribution in Scotland.

Did you know?

Bullheads are crepuscular: they spend their days hiding under stones, and venture out at dawn and dusk to hunt for prey.

How people can help

The Wildlife Trusts work with planners, water companies, landowners, statutory bodies and anglers to help make our waterways and waterbodies as good for wildlife as they are for people. By working together, we can create Living Landscapes: networks of habitats stretching across town and country that allow wildlife to move about freely and people to enjoy the benefits of nature. Support this greener vision for the future by joining your local Wildlife Trust.