Fish oil is the major source of omega-3 in fortifying foods, and accounts for 85% of the omega-3 food fortification market. Here, fish oil is typically sourced from anchovies, sardines, mackerel, herring, menhaden, and other fish species. The typical DHA:EPA ratio is 12:18. Such fish oils are the dominant omega-3 source in softgel capsule Omega-3/Fish Oil supplements. A minor portion of the fish oil is sourced from tuna. Some tuna species have naturally high DHA levels, i.e, 25:5 DHA:EPA which closely matches human breast milk  (DHA:EPA ratio 4.2:1) designed by nature for optimal infant growth and development. Such prized tuna oil is used mainly in fortifying infant formula.

Fish oil concentrates are fish oil that has undergone fractionisation to boost their concentration of DHA and/or EPA This is to facilitate high levels of omega-3 incorporation in foods so as to qualify labelling claims.

Marine oil particularly of oily fishes are rich sources of Omega – 3 Triglycerides, in particular Eicosapentaenoic Acid (EPA) and Docosahexanoic Acid (DHA).