Also known as a gwyniad, powan or shelly, the common whitefish is a member of the salmon family. It has a silver coloured streamlined body and darker coloured fins. It may reach up to 73 cm in length. Its tail fin is forked. Coregonus lavaretus has a small mouth and a protruding upper jaw.The few remaining UK populations are under considerable threat from a variety of problems including pollution, eutrophication and competition from introduced species including Gymnocephalus cernuus (IUCN, 2003).