freshwater
Brown Trout
Salmo trutta
Streamlined, torpedo-shaped body with a relatively large head. Features a square-cut tail fin and small scales. Coloration typically varies from golden-brown to olive on the back and sides, fading to a yellowish-white belly.…
- Habitat
- Found in cold, clear freshwater streams, rivers, and dee…
- Size & weight
- Typically ranges from 30 to 80 cm in length and 0.5 to 5…
- Diet
- Carnivorous. Feeds primarily on aquatic and terrestrial…
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Physical characteristics
Streamlined, torpedo-shaped body with a relatively large head. Features a square-cut tail fin and small scales. Coloration typically varies from golden-brown to olive on the back and sides, fading to a yellowish-white belly. Marked with distinct dark spots, often surrounded by lighter halos, and occasionally red or orange spots along the flanks.
Habitat & distribution
Found in cold, clear freshwater streams, rivers, and deep lakes. Native to Europe and Asia, but widely introduced globally in temperate regions. Prefers well-oxygenated waters with plenty of cover such as undercut banks, submerged logs, and boulders.
Behavior
Generally solitary and territorial as adults, establishing and defending specific feeding stations. Most active during low-light conditions such as dawn and dusk (crepuscular).
Diet
Carnivorous. Feeds primarily on aquatic and terrestrial insects, crustaceans, mollusks, and smaller fish, using both drift-feeding and ambush tactics.
Reproduction
Anadromous or freshwater-resident. Spawns in autumn and early winter in shallow gravel riffles. Females excavate a redd in the gravel to deposit eggs, which are then fertilized by males before being covered with substrate.
Ecological role
Acts as both an apex predator in many freshwater ecosystems and prey for larger piscivorous birds and mammals, helping regulate aquatic invertebrate and smaller fish populations.
Similar species
Brook Trout (Salvelinus fontinalis) and Rainbow Trout (Oncorhynchus mykiss). Brown trout can be distinguished by the lack of dark markings on the tail fin and the presence of light halos around dark spots on the body.
Identification tips
Look for dark spots with pale halos on the sides and an absence of spots on the caudal (tail) fin.
Interesting facts
Brown trout were one of the first exotic fish species successfully introduced outside their native range, with translocations beginning in the late 19th century.