New research from Nofima and Cargill reveals that while rainbow trout and salmon are often treated as interchangeable in aquaculture, their nutritional needs and processing abilities are surprisingly different.
Key Findings: Storage vs. Benefit
The study, conducted across full-scale sea-cage trials and indoor comparative labs, highlighted a significant biological divide:
- Efficient Accumulation: Rainbow trout are superior at storing omega-3s in their fillets compared to salmon. On the same diet, trout stored significantly more EPA and DHA.
- The “Health Ceiling”: Unlike salmon, which often show improved health and robustness when given extra omega-3s, rainbow trout saw no additional benefits in survival, growth, or welfare from elevated levels.
- Consumer Impact: Even on a “standard” diet, a single 125g serving of rainbow trout meets the daily EPA/DHA requirement for adults (250mg) recommended by the EFSA.
Data Comparison: EPA+DHA Content
The following table illustrates the omega-3 levels found per gram of fillet during the trials:
| Species | Feed Type | Omega-3 (mg/g) |
| Rainbow Trout | Standard | ~20 mg |
| Rainbow Trout | Elevated | ~26 mg |
| Atlantic Salmon | Elevated | ~16 mg |
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Why This Matters for the Industry
As marine fatty acids are a finite and expensive resource, these findings suggest that “one size fits all” feeding strategies are inefficient.
“Even though I get more than my daily requirement with the high omega-3 feed, that does not necessarily mean that this level represents good overall resource use,” explains Marta Bou, scientist at Nofima.
While salmon dominate the Norwegian market (accounting for 94% of sales compared to trout’s 6%), the industry is realizing that trout-specific research is vital to avoid wasting nutrients that don’t actually improve the fish’s well-being.