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
Native to Europe, from Iceland and Scandinavia south to the Atlas Mountains of North Africa and east through Turkey to the Caspian basin. The species (Salmo trutta) is one of the most widely introduced freshwater fish in the world, now established on every continent except Antarctica. Brown trout are found in cold, well-oxygenated rivers and lakes. They're closely related to Atlantic salmon (same genus, Salmo) and share similar habitat requirements. Brown trout are arguably the most culturally important freshwater fish in Europe, central to the fly-fishing tradition and to regional cuisines from Scandinavia to the Mediterranean. The flesh is white to pink, firm, and well-flavored. Brown trout aquaculture is established primarily in Europe and is smaller in scale than rainbow trout farming.
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 aquaponics species with characteristics between rainbow trout and brook trout. Optimal temperature is 12–18°C, with tolerance up to about 24°C (slightly warmer than brook trout, slightly cooler than rainbow trout). Growth: 300–500 g in 14-20 months on salmonid pellet (40-45% protein). FCR is 1.2-1.5, comparable to rainbow trout. Brown trout are notably more aggressive and territorial than rainbow trout, which affects stocking density: keep at 15-25 g/L, and provide structure (pipe sections, shaded areas) to reduce territorial disputes. They're also harder to train to pelleted feed than rainbow trout; source fingerlings that have been weaned onto pellets early. Dissolved oxygen above 6 mg/L; ammonia below 1 mg/L. Brown trout are more disease-resistant than rainbow trout in some contexts, particularly against whirling disease (Myxobolus cerebralis), which devastates rainbow trout populations but affects brown trout less severely. Fingerlings are available from trout hatcheries, primarily in the eastern US and Europe. Legal in most jurisdictions where trout culture is permitted. Brown trout are the best choice for aquaponics operators in Europe who want a native cold-water species, and a reasonable alternative to rainbow trout in North American cold-water systems.