Lake trout (Salvelinus namaycush) is a freshwater char living mainly in lakes in northern North America. Other names for it include mackinaw, lake char (or charr), touladi, togue, and grey trout. In Lake Superior, they can also be variously known as siscowet, paperbellies and leans. Lake trout are prized both as game fish and as food fish.
From a zoogeographical perspective, lake trout are quite rare. They are native only to the northern parts of North America, principally Canada but also Alaska and, to some extent, the northeastern United States. Lake trout have been introduced into many other parts of the world, mainly into Europe but also into South America and certain parts of Asia. Approximately 25% of the world's lake trout lakes are found in the province of Ontario, Canada. Even at that, only 1% of Ontario's lakes contain lake trout.
Lake trout are the largest of the charrs, the record weighing almost 46.3 kg (102 lb).
Lake trout inhabit cold, oxygen-rich waters. They are pelagic during the period of summer stratification in dimictic lakes, often living at depths of 20–60 m (60–200 ft).