Stone loach ( barbatula barbatula)
Between 3 and 5 cm
 The stone loach is a small native bottom dwelling fish  common and widespread across the UK. It is found in small streams, rivers, lakes they are omnivorous and will eat  small creatures, including small aquatic insects, midge larvae, zooplankton and worms as well as some plant material. They can also be fed frozen bloodworm, daphnia, flake food or sinking pellets. Stone loach  live between  3 and 7 years depending on water conditions and a temperature of 8 - 20° c is preferred. With good availability of food they can reach a max size of 15 cm, however a size of 10 to 12 cm is more common ,its small size makes it highly suitable for wildlife ponds ,while the stone loach prefers running water it will also thrive in still water provided there is good aeration .