Brown Trout Science and Facts

A freshwater dweller, the brown trout is a medium-sized fish with deep gold and brown coloring and a white or cream-colored belly. Large dark and red spots surrounded by a light halo cover its back, fading to smaller spots along the sides of the body. The tail has very few spots, distinguishing it from both the rainbow and brook trout which have many spots on their tails.


Similar in shape to the Atlantic salmon, the brown trout has an adipose fin which is the tiny fin between the back dorsal fin and the square-shaped tail. They generally grow to 10-15 inches in length and weigh between four and five pounds, but have been found as big as 25 inches in length and 12 pounds in weight. While it is from the same species as the sea trout, the brown trout is not migratory like the sea trout.

Brown trout have a highly developed sense of sight and hearing and rows of sharp, pointed teeth. Those sharp teeth give a nod to its carnivorous nature. Brown trout feast upon aquatic insects, pupae, insect larvae, nymphs, mayflies, crayfish, crustaceans, snails and small invertebrates such as other fish and frogs.


Native to Europe, western Asia and northeast Africa, the brown trout was first introduced into North America in the 1800s and can be found in freshwater lakes, swift streams and clear creeks across the United States and Canada. They prefer fresh, clean water in the 54-67 degree range but can tolerate water up to 70 degrees.


The spawning habits of brown trout are similar to those of the salmon, however, brown trout do not die after spawning. Brown trout continue to live in the same general area and come back to spawn over multiple years near the same location. Spawning season begins in October and runs into December.

When spawning season begins, the fish swim upstream to a spot with a gravel bottom and moving water. The female makes a saucer-shaped hole in the gravel where she will deposit the eggs and the male protects the nest until the female is ready. When ready, the female lays the eggs and the male fertilizes them at the same time. The female then covers the eggs with gravel. This process is repeated until the female has laid all of her eggs. One female can lay between 400 and 2,000 eggs depending upon her size.

After fertilization, the parents swim back to their home waters. The eggs will stay in the gravel-covered hole over the winter and hatch in the spring. Brown trout take three to four years to fully mature and have an average life span of about ten to twelve years. A brown trout and a brook trout will produce a tiger trout.

Some Facts:

The main predators of the brown trout are bigger fish and humans. Due to their elusive nature and keen sense of sight and sound, combined with a tendency to hide at the slightest movement, brown trout are not often caught by fishermen or found by bigger fish.

The brown trout is a popular game or sport fish, providing anglers with the opportunity to practice patience and skill. They are best caught with the dryflies and streamers of fly-fishing or the spoons, spinners and plugs of spin-fishing.

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