Arctic char or Arctic charr (Salvelinus alpinus) is a cold-water fish in the family Salmonidae, native to alpine lakes and arctic and subarctic coastal waters. Its distribution is circumpolar. It breeds in fresh water, and populations can either be landlocked or anadromous, migrating to the sea. No other freshwater fish is found as far north; it is, for instance, the only fish species in Lake Hazen on Ellesmere Island in the Canadian Arctic. It is one of the rarest fish species in Britain, found mainly in deep, cold, glacial lakes, and is at risk from acidification. In other parts of its range, such as Scandinavia, it is much more common, and is fished extensively. In Siberia, it is known as golets and it has been introduced in lakes where it sometimes threatens less hardy endemic species, such as the small-mouth char and the long-finned char in Elgygytgyn Lake.