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.
Enw gwyddonol
Cottus gobio
Pryd i'w gweld
January to December
Top facts
Stats
Length: 8-12cm
Weight: 6-12g
Average Lifespan: 3-4 years
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.
What to look for
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.
Where to find
Mainly found in England and Wales, limited distribution in Scotland.
Roeddech chi yn gwybod?
Bullheads are crepuscular: they spend their days hiding under stones, and venture out at dawn and dusk to hunt for prey.
