Bullhead (Cottus Gobio)

A small, nocturnal fish that spends its days concealed beneath stones at the bottom of a stream or riverbed might not seem like an obvious species to feature in a wildlife safari. However, the very presence of Bullhead in a watercourse speaks volumes about its natural condition and, for that reason, they are a key freshwater species…

ID: while it might lack horns, this species wide, flattened head and gaping mouth certainly ensure it lives up to its name and, if you’re lucky enough to see a Bullhead, make it easy to identify. With an equally distinctive tapering body these little fish (which rarely grow beyond fifteen centimetres in length) could never be accused of being indistinct! However, to blend into their surroundings, they also have mottled and scaleless skin that changes shade to achieve just that effect! This is also important because Bullhead feed on insect larvae and small crustaceans, relying on large, prominent eyes (which are situated atop their heads) to track movement before ambushing their prey in a short sharp dart across the riverbed.

Bullhead are excellent indicators of healthy freshwater habitat (Mark Sisson)
In the Field: Bullhead are not strong swimmers, so tend to favour moderately flowing freshwater rivers and streams. They are regularly found in the headwaters of lowland watercourses but adult fish need stretches with plenty of naturally wooded shade and aquatic cover because their size makes them vulnerable to larger predatory fish and bird species. Sinuous channels with stony shallows, small pools and riffles are also important for young fish, while clean gravels are necessary during breeding — when males excavate nests for females to lay their eggs on the undersides of larger stones.
How Are They Doing?
Although widely distributed throughout England and Wales the varied habitat requirements that make Bullhead such good indicators of heathy waterway habitat also mean they are very sensitive to change. Silt deposited in stream and riverbeds from surrounding farmland, dredging and other activities that modify watercourses (such as straightening and widening) can all badly affect local bullhead populations.

On the Weald Moors: Bullhead have been recorded in the River Strine on Tibberton Moor,  in the River Tern at Crudgington and, most recently, in the waterways adjacent to Kynnersley Drive. They are territorial fish and evidence suggests adults do not tend to stray far beyond their home stones, although competition for the best sheltering and hunting sites can be intense, which may cause some fish to move sites.


Weald Moors Habitat: Rivers, Streams and Strines

With thanks to Mark Sisson for allowing us permission to reproduce his stunning Bullhead image