• Bullheads are sometimes known as Millers thumb, but their scientific name is Cottus gobio.
• They like to live in fast flowing stony rivers and streams, such as sections along the Bourne, hiding in amongst the rocks from larger fish like Brown trout.
• They feed on invertebrates including mayfly nymphs, caddisfly larvae and freshwater shrimp, which also live among the gravel.
• Bullheads can live for up to 4 years, growing to a maximum size of approximately 12cm.
• Bullheads are normally brown, with a variety of markings depending on what best suits their habitat, however, during breading season the males turn black with white tipped dorsal fins.