Brown Trout (Salmo trutta)
Current record: 31lb 12oz
Water: Loch Awe, Ardbrecknish
The brown trout (Salmo trutta) is native to Europe and western Asia, and has been introduced to trout waters worldwide since. Colouring runs from olive-green to golden-brown, scattered with red and black spots, and spawning males develop a hooked lower jaw (a kype) along with noticeably brighter colours.
There's more variety within the species than the name suggests. Some populations stay in freshwater their whole lives; others, sea trout, migrate to saltwater and back to spawn, adding a genuinely different angling target under the same species. Sea trout pick up regional names depending where you're fishing them: sewin in Wales, finnock in Scotland, peal in the West Country, mort in North West England, and white trout across the water in Ireland.
They're adaptable fish, turning up in anything from small upland streams to big lowland rivers and stillwaters, and they'll eat almost anything that moves: insects, small fish, crustaceans, even the odd small mammal that ends up in the water. That range makes them a genuine test for fly anglers, matching what a brown trout's actually feeding on, rather than what's in the box, is most of the challenge.
Wild brown trout populations depend heavily on clean, well-oxygenated water and intact spawning gravel, which is why habitat and water quality work tends to matter more for this species than stocking numbers alone.