A spot of pond dipping with my daughter, at a local nature reserve's summer event, turned up a great find: a bullhead lurking in the mud. It's perhaps 7cm long and quite chunky with a great big head, hence the name bullhead, and the alternative name miller's thumb.

They tend to live at the bottom of fast flowing stony rivers, feeding on invertebrates at dusk. They are very well camouflaged – unless you stick them in a white tray of course – and swim very well.