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, remaining in fresh water for their entire life cycle, or anadromous, where they return from the ocean to their fresh water birth rivers to breed. 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.

The Arctic char is closely related to both salmon and lake trout, and has many characteristics of both. The fish is highly variable in colour, depending on the time of year and the environmental conditions of the lake where it lives. Individual fish can weigh 20 lb (9.1 kg) or more with record-sized fish having been taken by anglers in northern Canada. Generally, whole market-sized fish are between 2 and 5 lb (0.91 and 2.27 kg). The flesh colour can range from a bright red to a pale pink.

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