Brown trout Salmo trutta

A medium to large fish, the brown trout lives in fast-flowing, stony and gravelly rivers. Brown trout are predatory fish, feeding on insect larvae, small fish and flying insects such as mayflies and damselflies. Spawning occurs between January and March when females (accompanied by a number of males) lay their eggs on gravelly beds. Fertilised externally, the eggs are buried in the gravel. The young fish (fry) hatch and feed on the nutritious yolk sac before moving on to feed on invertebrates.


The brown trout is a silvery-brown fish with a dark back and creamy-yellow belly. The back and sides are spotted with reddish spots with pale borders. Much smaller than the Atlantic salmon. It can be distinguished from the rainbow trout by its plain, dark tail fin and the lack of a purple side-stripe.


  • Length: 50-80cm
  • Weight: up to 2kg
  • Average Lifespan: up to 5 years


Classified as a Priority Species in the UK Biodiversity Action Plan.


Found throughout the country in rivers,lochs and upland lochans.

When to see

January – December


  • Sea trout and brown trout have recently been recognised as the same species: the former is migratory, spending most of its life at sea and returning to freshwater to spawn; the latter spends all of its life in freshwater.
  • A trout can look and focus out of both corners of each eye simultaneously meaning that it can see in almost every direction at once.

Common name

Brown trout

Species name

Salmo trutta

IUCN Red List status

Least concern

When to see in Scotland

January – December

Where to see in Scotland

Scottish Wildlife Trust reserves such as Rahoy Hills or Ben Mor Coigach.

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