trout: see salmon.

sea trout: see croaker.

Any of several prized game and food fishes of the family Salmonidae, native to the Northern Hemisphere but widely introduced elsewhere. Though most species inhabit cool fresh waters, a few (called sea trout; e.g., cutthroat trout) migrate to the sea between spawnings. Some weakfish are also called sea trout. The genus Oncorhynchus includes salmon and several trout species; Salvelinus contains trout species regarded as chars. Trout species vary greatly in anatomy, colour, and habits. Most live among submerged objects or in riffles and deep pools, eating insects, small fishes and their eggs, and crustaceans. Seealso brook trout; brown trout; lake trout; rainbow trout.

Learn more about trout with a free trial on Britannica.com.

or speckled trout

Popular freshwater game fish (Salvelinus fontinalis), a variety of char, that is valued for its flavour and its fighting qualities when hooked. The brook trout is a native of the northeastern U.S. and Canada and has been transplanted to many parts of the world. It lives in cold, clean waters and carries dark, wormlike markings on the back and red and whitish spots on the body. The brook trout may weigh up to 6 lbs (3 kg). Some individuals migrate to large lakes or the sea and grow much larger and more silvery.

Learn more about brook trout with a free trial on Britannica.com.

or sea trout

Any of several species (genus Cynoscion) in the drum family (Sciaenidae), carnivorous bottom-dwelling fishes along warm and tropical seashores. The name weakfish refers to their delicate mouth, which is easily torn by fishhooks. About six species inhabit North American coasts. The weakfish, or sea trout (Cynoscion regalis), is a sport fish but is usually less than 2 ft (60 cm) long. Weakfish are caught commercially along the Middle Atlantic coastal states and are considered the most economically important species in the family. The spotted sea trout (C. nebulosus) is found along Florida's Atlantic and Gulf coasts. Sea trouts resemble but are not related to true trouts.

Learn more about weakfish with a free trial on Britannica.com.

or Mackinaw trout or Great Lakes trout or salmon trout

Large, voracious char (Salvelinus namaycush) found widely from northern Canada and Alaska to New England and the Great Lakes, usually in deep, cool lakes. They are greenish gray and covered with pale spots. In spring, 5-lb (2.3-kg) lake trout are caught in shallow water; in summer, fish of up to 100 lbs (45 kg) are trolled in deep water. Lake trout were virtually eliminated from the Great Lakes by the sea lamprey, which entered through the Welland Canal in the 1930s. They have been introduced in the western U.S., South America, Europe, and New Zealand.

Learn more about lake trout with a free trial on Britannica.com.

Species (Oncorhynchus mykiss) of fish in the salmon family (Salmonidae) noted for spectacular leaps and hard fighting when hooked. It has been introduced from western North America to many other countries. A brightly coloured fish of lakes and swift streams, it is covered with small black spots and has a reddish band along either side. The steelhead, a large, bluish, oceangoing form, is also a prized game fish. Rainbow trout may weigh 6 lb (2.8 kg); steelheads (and rainbows in large lakes) may weigh 10–20 lb (4.5–9 kg) or more. Another form of rainbow, the Kamloops, or Kootenay, trout of Idaho, may exceed 30 lb (14 kg).

Learn more about rainbow trout with a free trial on Britannica.com.

Black-spotted game fish (Salmo clarki) of the salmon family, found in western North America. The cutthroat trout is named for the bright red streak beneath its lower jaw. Considered a good table fish, it strikes at flies, baits, and lures. It reaches a weight of 4 lb (1.8 kg). Many cutthroat trout that live in rivers migrate to sea. Like oceanic forms of other trout species, these fish are called sea trout and may not reenter freshwater for several years.

Learn more about cutthroat trout with a free trial on Britannica.com.

Prized and wary European game fish (Salmo trutta, family Salmonidae) that is favoured for food. The species includes several varieties (e.g., the Loch Leven trout of Britain). The brown trout is recognized by the light-ringed black spots on its brown body. It has been transplanted to many areas of the world because it can thrive in warmer waters than most other trout. It grows to about 8 lbs (3.6 kg). Oceangoing individuals, called sea trout, are larger than freshwater forms and provide good sport, as do those that enter large lakes.

Learn more about brown trout with a free trial on Britannica.com.