Last update: 19 November 2020

Fish are the major dietary source of the polyunsaturated n-3 fatty acids EPA and DHA. This makes them a potent tool in managing your n-3 to n-6 fatty acid composition, which you may want to do to improve your health1,2,3. However, not all fish are created equal, and farmed fish have distinct lipid profiles from wild fish, where the farmed varieties have much more linoleic acid4,5,11. The total amount of fat4 needs to be considered as well, since all the fish in the world won’t make a difference if they are too lean.

In general, I think it’s vastly preferable to eat wild fish over farmed fish. Sometimes, fish are labelled as to their origin (farmed or caught), but often they are not. Distinguishing them can be a problem, one possible solution to which would be to look at which fish species are mentioned in aquaculture analyses. For example, in one document about Polish aquaculture6 lists 29 fish species produced, among others carp (several species), trout (several species), sturgeon, salmon (two species), pike, catfish and tench. I wouldn’t eat any of the fish on that list regularly, on account of them linoleate content, since anything I find in the shops is likely to originate from these fish farms.

Specific recommendations are difficult to give, since type of aquaculture and access to global food supply differ between regions. However, two fish species that I’ve never heard about being farmed for human consumption are sprat7 and herring7,8 (do correct me if I err). Given the publications on the matter of fatty acid profiles9,10,11, mackerel also seems very likely not to come from farms.

A frequent objection to fish consumption is the danger of methylmercury poisoning. While this is a real concern12, they need not be eaten in such amounts as to cause significant risk – 50-100 grams fatty fish per day is probably more than enough. Furthermore, bioavailability13 and amount of mercury vary considerably across particular fish and locations14,15. Small fish, low on the trophic level (such as sprat and small herring), tend to have less mercury15.


  1. Simopoulos AP, DiNicolantonio JJ. The importance of a balanced ω-6 to ω-3 ratio in the prevention and management of obesity. Open Heart. 2016;3(2):e000385. Published 2016 Sep 20. doi:10.1136/openhrt-2015-000385
  2. Casula M, Olmastroni E, Gazzotti M, Galimberti F, Zambon A, Catapano AL. Omega-3 polyunsaturated fatty acids supplementation and cardiovascular outcomes: do formulation, dosage, and baseline cardiovascular risk matter? An updated meta-analysis of randomized controlled trials. Pharmacol Res. 2020 Oct;160:105060. doi: 10.1016/j.phrs.2020.105060. Epub 2020 Jul 4. PMID: 32634581.
  3. Hamazaki T, Okuyama H. The Japan Society for Lipid Nutrition recommends to reduce the intake of linoleic acid. A review and critique of the scientific evidence. World Rev Nutr Diet. 2003;92:109-32. doi: 10.1159/000073796. PMID: 14579687.
  4. Kaliniak, Agnieszka & Florek, Mariusz & Skałecki, Piotr. (2015). Profil kwasów tłuszczowych mięsa, ikry i wątroby ryb/Profile of fatty acids in meat, roe, and liver of fish. Zywnosc: Nauka, Technologia, Jakosc. 99. 29-46. 10.15193/zntj/2015/99/020.
  5. Lundebye AK, Lock EJ, Rasinger JD, Nøstbakken OJ, Hannisdal R, Karlsbakk E, Wennevik V, Madhun AS, Madsen L, Graff IE, Ørnsrud R. Lower levels of Persistent Organic Pollutants, metals and the marine omega 3-fatty acid DHA in farmed compared to wild Atlantic salmon (Salmo salar). Environ Res. 2017 May;155:49-59. doi: 10.1016/j.envres.2017.01.026. Epub 2017 Feb 9. PMID: 28189073.
  6. Andrzej Lirski, Leszek Myszkowski. Zakład Rybactwa Stawowego w Żabieńcu, Instytut Rybactwa Źródłdowego w Olsztynie. Polska akwakultura w 2016 roku na podstawie analizy kwestionariuszy RRW-22. Część 1. 2017.
  7. Keinänen, Marja & Käkelä, Reijo & Ritvanen, Tiina & Myllylä, Timo & Pönni, Jukka & Vuorinen, Pekka J.. (2017). Fatty acid composition of sprat (Sprattus sprattus) and herring (Clupea harengus) in the Baltic Sea as potential prey for salmon (Salmo salar). Helgoland Marine Research. 71. 10.1186/s10152-017-0484-0.
  8. Jensen, Kristina & Jacobsen, Charlotte & Nielsen, Henrik. (2007). Fatty acid composition of herring (Clupea harengus L.): Influence of time and place of catch on n-3 PUFA content. Journal of the Science of Food and Agriculture. 87. 710 – 718. 10.1002/jsfa.2776.
  9. Nazemroaya, Samira & Sahari, Mohammad Ali & Rezaei, Masoud. (2011). Identification of Fatty Acid in Mackerel (Scomberomorus commersoni) and Shark (Carcharhinus dussumieri) Fillets and Their Changes during Six Month of Frozen Storage at -18˚C. Journal of Agricultural Science and Technology. 13. 553-566.
  10. Nurjanah, Nurjanah & Nurilmala, Mala & Hidayat, Taufik & Yulia, Rahma & Azri, Idhviani. (2016). Fatty Acid Composition and Cholesterol Indian Mackerel (Rastrelliger kanagurta) Due Frying Process. International Journal of Materials Chemistry and Physics. 2. 54-61.
  11. Huang LT, Bülbül U, Wen PC, Glew RH, Ayaz FA. Fatty acid composition of 12 fish species from the Black Sea. J Food Sci. 2012 May;77(5):C512-8. doi: 10.1111/j.1750-3841.2012.02661.x. Epub 2012 Apr 12. PMID: 22497457.
  12. Silbernagel SM, Carpenter DO, Gilbert SG, et al. Recognizing and preventing overexposure to methylmercury from fish and seafood consumption: information for physicians. J Toxicol. 2011;2011:983072. doi:10.1155/2011/983072
  13. Bradley MA, Barst BD, Basu N. A Review of Mercury Bioavailability in Humans and Fish. Int J Environ Res Public Health. 2017;14(2):169. Published 2017 Feb 10. doi:10.3390/ijerph14020169
  14. Tollefson L, Cordle F. Methylmercury in fish: a review of residue levels, fish consumption and regulatory action in the United States. Environ Health Perspect. 1986;68:203-208. doi:10.1289/ehp.8668203
  15. Buck DG, Evers DC, Adams E, DiGangi J, Beeler B, Samánek J, Petrlik J, Turnquist MA, Speranskaya O, Regan K, Johnson S. A global-scale assessment of fish mercury concentrations and the identification of biological hotspots. Sci Total Environ. 2019 Oct 15;687:956-966. doi: 10.1016/j.scitotenv.2019.06.159. Epub 2019 Jun 12. PMID: 31412499.