Salmo trutta levenensis Walker. Loch Leven Trout
Author Barton Warren Evermann (1853–1932)
Subject: Brown trout
Date 1891
Source/Photographer Evermann, Barton W. (1893) Reconnaissance of the streams and lakes of western Montana and northwestern Wyoming, Bulletin of the United States Fish Commission, vol. 11, 1891, Washington, DC: Government Printing Office
Source: https://commons.wikimedia.org/wiki/File:FMIB_34337_Salmo_trutta_levenensis_Walker_Loch_Leven_Trout.jpeg

The brown trout (Salmo trutta) is a European species of salmonid fish (Salmonidae) that has been widely introduced into suitable environments globally. The native range of brown trouts extends from northern Norway and White Sea tributaries in Russia in the Arctic Ocean to the Atlas Mountains in North Africa. The western limit of Salmo trutta is Iceland in the north Atlantic, while the eastern limit is in Aral Sea tributaries in Afghanistan and Pakistan.

Freshwater brown trout range in colour from largely silver with relatively few spots and a white belly, to the more well-known brassy reddish-brown cast fading to creamy white on the fish's belly, with medium-sized spots surrounded by lighter halos. The more silver forms can be mistaken for rainbow trout. Regional variants include the so-called "Loch Leven" trout, distinguished by larger fins, a slimmer body, and heavy black spotting, but lacking red spots. The continental European strain features a lighter golden cast with some red spotting and fewer dark spots. Notably, both strains can show considerable individual variation from this general description. Early stocking efforts in the United States used fish taken from Scotland and Germany.

Order: Salmoniformes
Family: Salmonidae
Genus: Salmo
Species: Salmo trutta Linnaeus, 1758