Crucian Carp Carassius carassius

The Crucian Carp has a long dorsal fin but is much smaller than the Common Carp with a deeper body ratio, a yellowish colouring, especially the underside, and red or reddish lower fins. Its tail is only very slightly forked. It grows typically to 15-25cm long. It is native to northern Europe (including the UK) and favours ponds, lakes and slow-moving canals/rivers where it is able to live in polluted and low-oxygenated water where other carp/fish cannot.

It is said to be the ancestor of the Goldfish (Carassius auratus) and can produce hybrids with feral goldfish. (The Prussian Carp, C. gibelio, with a more forked tail, is also said to be the goldfish ancestor.)