Bullheads, also known as the miller’s thumb, are small fish (maximum length 18 cm), with a large mouth, large pectoral fins, prominent eyes and a wide flattened head. They are mottled brown on top, with a pale belly. Male bullheads turn black with a white-tipped dorsal fin in the breeding season, and females become plump.  

Bullheads are crepuscular – they spend the day hiding under stones or in vegetation, and come out at dusk to feed. They are widely distributed in England, and are found in streams, rivers and lakes with hard stony substrates, preferring shallow, fast-flowing water bodies. Bullheads lay their eggs underneath stones or in a pit. Male bullheads guard the eggs and fan them keep up a good supply of oxygen. Bullheads are prey for many different species, including brown trout, pike, grey heron, kingfisher and dippers.

The bullhead is threatened, and several areas of land in the UK have been selected as candidate Special Areas of Conservation (SACs) to help conserve this fish. However, more needs to be done to maintain the UK population - information on where the bullhead occurs in Leicestershire and Rutland will help.

More information and images of bullheads are available on the Arkive website.  http://www.arkive.org/species/ARK/fish/Cottus_gobio/