freshwater
Brown Trout
Salmo trutta
Elongated, torpedo-shaped body with small scales. Olive-green to brown back and sides fading to a yellowish-white belly. Distinctive dark spots, often surrounded by lighter halos, along with red or orange spots scattered on the sides and flanks.…
- Habitat
- Found in cold, clear, well-oxygenated streams, rivers, a…
- Size & weight
- Typically 14 to 20 inches and 1.5 to 3 pounds, with maxi…
- Diet
- Carnivorous, feeding on aquatic and terrestrial insects,…
Identified More freshwater →
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Physical characteristics
Elongated, torpedo-shaped body with small scales. Olive-green to brown back and sides fading to a yellowish-white belly. Distinctive dark spots, often surrounded by lighter halos, along with red or orange spots scattered on the sides and flanks. Features a square-cut tail fin with few or no spots, and an adipose fin near the tail.
Habitat & distribution
Found in cold, clear, well-oxygenated streams, rivers, and deep lakes. Native to Europe and Asia, but widely introduced globally in temperate regions.
Behavior
Generally solitary and territorial as adults, establishing and defending specific feeding stations. Primarily crepuscular and nocturnal, showing increased activity at dawn, dusk, and during overcast days.
Diet
Carnivorous, feeding on aquatic and terrestrial insects, crustaceans, mollusks, and smaller fish, employing both drift-feeding and ambush strategies.
Reproduction
Spawns in autumn and early winter. Females dig a shallow depression called a redd in gravelly stream beds, deposit eggs, and cover them after fertilization. Juveniles hatch in winter or spring.
Ecological role
Acts as an apex predator in many freshwater ecosystems, regulating populations of smaller fish, aquatic insects, and macroinvertebrates.
Similar species
Rainbow Trout (Oncorhynchus mykiss), which has a pinkish-red stripe along its side and numerous small spots covering the tail; and Brook Trout (Salvelinus fontinalis), which features worm-like patterns on its back and white-edged lower fins.
Identification tips
Look for the squared-off tail fin with very few or no dark spots, large dark spots surrounded by lighter halos, and the presence of red or orange spots on the sides.
Interesting facts
Brown Trout were among the first fish species to be widely introduced outside their native range, beginning in the late 19th century. They are known for becoming increasingly cautious and difficult to catch as they grow larger.