It is one of the rarest fish species in Great Britain and Ireland, found mainly in deep, cold, glacial lakes, and is at risk there from acidification.

The fish is highly variable in colour, depending on the time of year and the environmental conditions of the lake where it lives.

The dorsal side of the Arctic char is dark in its colour while the ventral varies from red, yellow, and white.

[12] The English name is thought to derive from Old Irish ceara/cera meaning "[blood] red",[13] referring to its pink-red underside.

[19]Arctic char is notable for exhibiting numerous, seemingly distinct morphological variants or 'morphs' throughout the range of the species.

[21][23][24] Morphs often interbreed, but they can also be reproductively isolated and represent genetically distinct populations,[24] which have been cited as examples of incipient speciation.

[30] Sparctic char grows faster than either parent species, are stronger and healthier, and are thus popular for sports fisheries.

[30] Sparctic char have been found locally in Sweden, for example in the Piteälven and Skellefteälven Rivers in the northern part of the country, though are believed to be relatively uncommon.

[31][32] Anadromous Arctic chars spend their juvenile years in fresh water, and once mature, migrate annually to the marine environment.

Generally, Arctic char inhabits shallow waters, rarely swimming deeper than 3 m (10 ft) depth.

[31][32] An exception to this applies to landlocked Arctic chars, which often swim much deeper in the summer in order to occupy colder waters.

[31][32] Dwarf Arctic chars are more common in landlocked populations as a result of scarce resources (immense competition).

[36][37] As ferox trout are an apex predator, Arctic char is thus a key species throughout many lakes in its range.

During the autumn and winter months, it feeds on zooplankton and freshwater shrimps that are suspended in the lake, and also occasionally on smaller fish.

The marine diet of Arctic char consists mostly of a copepod species (Calanis finmarchicus) and krill (Thysanoëssa).

[4][32][38][39] Spawning occurs over rocky shoals in lakes with heavy wave action and in slower gravel-bottom pools in rivers.

As with most salmonids, vast differences in colouration and body shape occur between sexually mature males and females.

Young Arctic char emerge from the gravel in spring and stay in the river from 5 to 7 months, or until they are about 15–20 cm (6–8 in) in length.

[36][40][41][42][43] Hatchlings are immediately independent of parents at hatching, and stay at the bottom of the gravel till they are 15–18 cm (6–7 in) in length.

Numerous commercial fisheries are located in river systems throughout the Canadian Arctic, with the majority in Nunavut, such as the areas of Cumberland Sound and Cambridge Bay.

Arctic char is also farmed in Iceland, Estonia, Norway, Sweden, Finland, West Virginia, and Ireland.

It could be an alternate species to rainbow trout (Oncorhynchus mykiss), and could provide producers with a different niche in the marketplace.

[9] Arctic char first exhibits a rapid growth spurt during this phase, reaching its market weight of 1–2.5 kg (2–6 lb) within a year.

[9] In 2006, Monterey Bay Aquarium Seafood Watch[46] program added farmed Arctic char as an environmentally sustainable Best Choice for consumers, stating: "Arctic char use only a moderate amount of marine resources for feed" and that they "are farmed in land-based, closed systems that minimize the risk of escape into the wild.