[3] Even some non-salmonid fish species are also commonly known as sea trout, such as Northern pikeminnow (Ptychocheilus oregonensis) and members of the weakfish family (Cynoscion).

Originally, the name Salmo trutta was used to refer specifically to the anadromous or sea-run forms of brown trout.

However, once they return to freshwater, they quickly take on the normal coloration of resident brown trout in preparation for spawning.

Sea trout kelts (post spawn) return to their silvery stage as they migrate back to saltwater.

Breeding males will develop a hook-like, upward-facing protrusion on the lower jaw called a kype.

In freshwater the top of the trout is an olive color with brown and black spots, with the ventral side being tan to yellow.

In the sea, it makes long journeys and also swims upstream into small rivers in order to spawn.

Fish that are ready for spawning are usually lean and have to eat a lot of food in order to increase their energy levels as quickly as possible.

In many rivers of Central Europe, the sea trout have been extirpated because hydropower plants prevent spawning migration.

In more recent times, sea trout have succeeded in re-establishing themselves in some lakes and rivers through the introduction of fish ladders and bypass channels around hydropower plants.

Sea trout are very easily "spooked" by bankside disturbance and during daylight hours tend to be tucked up under the banks and submerged tree roots, and therefore very hard to catch.

When the rivers are flowing coloured in a spate following heavy rain, it is possible to catch sea trout during the day with artificial lures or spinners.