Farmed vs Wild Fish: Omega-3 Content and Contaminants
What composition studies and USDA data show about EPA and DHA in farmed and wild salmon, and about the contaminants measured, with no universal winner.
Content last updated . This page has not been medically reviewed.
The question
Is farmed or wild fish the better source of omega-3, and which carries more contaminants? The studies we read say the answer depends on what you measure. Wild salmon had a higher share of long-chain omega-3 in the fat, but farmed salmon had more fat, so a portion could hold as much or more EPA and DHA. Wild salmon had higher levels of some contaminants, all below legal limits in the one study that measured them. This page covers fatty acids and the contaminants named in the studies; it does not cover antibiotics, parasites, sustainability or taste, which we did not search for.How the sources define the terms
Farmed fish are raised in pens or tanks and fed prepared feed. Wild fish are caught from open water. Both are the same species of salmon in these studies. "Proportion" means the share of omega-3 among all fatty acids; "absolute amount" means grams per 100 g of fillet. The two can point in opposite directions.What the studies found
| Question | What the source found | Strength of evidence |
|---|---|---|
| Omega-3 share vs total amount (Norway, 2020) | Farmed (n = 20), escaped (n = 17) and wild (n = 23) Atlantic salmon fillets. Fat in farmed salmon was 18%, three times the wild fish, while marine long-chain omega-3 made up 8.9% of fatty acids in farmed versus 24.1% in wild. The authors called both farmed and wild salmon valuable sources of EPA and DHA. [1] | One country, one species, small samples; direct measurements |
| Portion "dose" (UK retail, 2014) | Wild products had higher proportions of long-chain omega-3 (20 to 40% versus 9 to 26%) but lower total fat (1 to 6% versus 7 to 17%); farmed products invariably had more EPA and DHA in absolute terms per 100 g. [2] | Retail survey; varies with feed |
| Salmon in Germany (2012) | Farmed salmon had higher fat than wild (12.3 versus 2.1 weight %), but also more saturated, omega-9 and omega-6 fat, from vegetable oils and oilseeds in feed. [3] | Market survey |
| Variation inside farmed fish (US, 2014) | Across 76 finfish species, large variance was found within many farmed species, likely from differences in feed. Salmon species ranged from 717 to 1,533 mg of EPA plus DHA per 100 g. [4] | Direct measurements of fillets from six US regions |
| Contaminants (Norway, 2020) | Dioxins, dioxin-like PCBs, mercury and arsenic were three times higher in wild than in farmed salmon, all well below EU maximum levels; the six ICES PCBs were 5.09 ng/g in wild and 3.34 ng/g in farmed. [1] | One study; a limit being met is not the same as no risk |
USDA numbers side by side
USDA FoodData Central (SR Legacy, 2018) lists Atlantic salmon separately for farmed and wild. [5]| USDA entry, grams per 100 g | EPA | DHA | EPA + DHA (our sum) |
|---|---|---|---|
| Atlantic, farmed, raw | 0.86 | 1.10 | 1.97 |
| Atlantic, wild, raw | 0.32 | 1.12 | 1.44 |
| Atlantic, farmed, cooked | 0.69 | 1.46 | 2.15 |
| Atlantic, wild, cooked | 0.41 | 1.43 | 1.84 |
Source: USDA FoodData Central, SR Legacy, April 2018 release. [5] Feeds have changed over time, so older entries may not describe fish sold today. The UK and German studies note that rising use of vegetable oil in feed lowered the share of long-chain omega-3 in some farmed products. [2][3]
No universal winner
The sources we read give no rule for choosing by label. For most readers, eating a variety of fish within official limits matters more than the farmed versus wild label.Frequently asked questions
Does farmed salmon have less omega-3 than wild?
Less as a share of its fat in two studies, but more fat overall, so a portion often had as much or more EPA and DHA. [1][2]
Is wild salmon more contaminated?
In a Norwegian study, dioxins, PCBs, mercury and arsenic were higher in wild salmon than farmed, all below EU limits. [1]
Is farmed salmon high in omega-6?
Studies in Germany and the UK found vegetable-oil signatures (omega-6 and omega-9 fats) in some farmed products. [3][2]
Which should I choose?
The studies do not name a winner. Variety within official limits is the common advice. [8]
Do supplements avoid these issues?
Proper evidence not found on this page, which covers fish as food; see the fish oil purity page.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Limits and uncertainty
- Feed matters more than the label. Within each group the studies found wide ranges, so "farmed" or "wild" alone does not predict omega-3 content. [2]
- Contaminant studies measure fish, not people. They report concentrations in fillets. A 2006 JAMA review concluded that levels of dioxins and PCBs in fish were low and that potential harms were outweighed by the benefits of fish intake; that review is from 2006 and predates the studies above. [6]
- Official advice does not split farmed and wild. The FDA and EPA list "Salmon" as a Best Choice for mercury without separating the two. [7] The NHS notes that oily fish usually have higher levels of pollutants than other seafood, which is why it caps portions for some groups. [8]
- Labels such as "organic" or "natural". Proper evidence not found in the sources we read; we did not search for them.
Safety and who should ask a clinician
Pregnant or breastfeeding women, people planning a pregnancy, and parents of young children should follow the official limits in official fish-eating advice and mercury. People with fish allergy should read fish allergy and omega-3 products. Amounts per species are in the fish and seafood content tables; the broader food page is oily fish. Questions about blood thinners or surgery belong to a pharmacist or clinician.
References
- Update on fatty acids, dioxins, PCBs and heavy metals in farmed, escaped and wild Atlantic salmon in Norway. Foods 2020. Read 2026-10-23.
- Nutritional quality of salmon products available from major retailers in the UK. Br J Nutr 2014. Read 2026-10-23.
- Survey of n-3 and n-6 polyunsaturated fatty acids in fish and fish products. Lipids Health Dis 2012. Read 2026-10-23.
- Fatty acid profiles of commercially available finfish fillets in the United States. Lipids 2014. Read 2026-10-23.
- USDA FoodData Central, SR Legacy dataset (April 2018 release, CSV download). Read 2026-10-23.
- Fish intake, contaminants, and human health: evaluating the risks and the benefits. JAMA 2006. Read 2026-10-23.
- FDA and EPA, Advice About Eating Fish (revised October 2021). Read 2026-10-23.
- NHS, Fish and shellfish. Read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.