Grayling, a slender freshwater game fish of the salmon family. The grayling is 12 to 18 inches (30 to 45 cm) long. It is grayish in color, with bluish spots on the upper abdomen. The scales and dorsal (back) fin are large. Graylings resemble trout in their habits, but spawn (lay eggs) in the spring rather than in the fall.
The European grayling, weighing about four pounds (1.8 kg), is found in cold streams from England eastward through Siberia. American species, which weigh about two pounds (0.9 kg), include the Alaska grayling, native to northwestern Canada, and the mountain grayling, found in the upper Missouri River and its tributaries. A third species, the Michigan grayling, is almost extinct.
The European grayling is Thymallus thymallus; Alaska grayling, T. signifer; mountain grayling, T. montanus; Michigan grayling, T. tricolor. All belong to the family Salmonidae.