Brown trout
Salmo trutta
Also known asLoch Leven trout
Water parameters
Minimum tank: 500 L per individual at harvest size.
Feed and growth
- Feed protein
- 45% target
- Daily feed (warm)
- 1.20% of body weight
- Daily feed (cool)
- 0.80% of body weight
- Max density
- 35 g per litre
A 1500 g adult eats about 18.0 g of feed per day at optimum. 10 fish at adult size: ~180 g daily.
Legality
Rules vary by jurisdiction and change over time. Verify with your local fisheries or wildlife authority before stocking.
| Jurisdiction | Status | Notes |
|---|---|---|
| California | permit required | verified 2026-05-13 |
| Montana | permit required | Montana requires aquaculture permit; introduction concerns for native cutthroat trout verified 2026-05-13 |
Unlisted jurisdictions default to "check local regulations".
Origin and habitat
Salmo trutta is native to cool fresh waters across Europe and beyond, from Iceland and the British Isles east to the Caspian basin, into western Asia, and south to the Atlas Mountains of North Africa. It is one of the most widely stocked freshwater fish in the world, now established on every continent except Antarctica through angling-driven introductions. The fish lives in cold, well-oxygenated rivers and lakes and is a close relative of the Atlantic salmon in the genus Salmo. It is arguably the most culturally significant freshwater fish in Europe, at the heart of the fly-fishing tradition and of regional cooking from Scandinavia to the Mediterranean. The flesh is white to pink, firm, and well flavored. Adults commonly run 30 to 50 cm and a kilogram or a few, though lake fish can grow much larger, and the species can live around twenty years. Brown trout farming is centered in Europe and runs at a smaller scale than rainbow trout.
Climate and outdoor ponds
- Climate
- cold-water (cool water required, dies in heat)
- USDA zones
- 3–7 (winter low around -40°C or warmer)
- Heating needed
- no
- Cooling needed
- yes, if summer water exceeds upper tolerance
Care notes
A cold-water species with fairly narrow thermal limits. It does best around 12–18°C and begins to stress near 20°C, with a lower limit around 4°C; in practice its temperature window is tighter than rainbow trout's, so steady cold water matters. Growth reaches 300–500 g in fourteen to twenty months on a salmonid pellet of 40 to 45 percent protein, with feed conversion around 1.2 to 1.5, much like rainbow trout. Brown trout are notably more aggressive and territorial than rainbow trout, which caps practical stocking at about 15 to 25 g/L and makes structure such as pipe sections and shaded areas worthwhile to break up disputes. They can also be harder to wean onto pellets, so it pays to start with fingerlings already trained to dry feed. Keep dissolved oxygen above about 6 mg/L and ammonia low. One advantage is disease: having evolved alongside whirling disease (Myxobolus cerebralis), brown trout resist it far better than rainbow trout, though they can still carry and spread it. Fingerlings come from trout hatcheries in the eastern US and Europe, and the fish is legal where trout culture is allowed, with permits required in some states over concerns about native trout. It is the natural pick for European growers wanting a native cold-water fish and a fair alternative to rainbow trout in North American cold systems.