Fish oil is oil derived from the tissues of oily fish and is an important source of Omega-3 fatty acids.
The fish used as sources do not actually produce omega-3 fatty acids, but instead accumulate them by consuming either microalgae or prey fish that have accumulated omega-3 fatty acids.
Our main focus is on eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are the two main long chain highly unsaturated fatty acids. They are primarily marine-derived. EPA and DHA are synthesized by algae and marine plants. The algae are eaten by zooplankton, the zooplankton by fish and on up the food chain. At each stage the EPA and DHA are retained and utilized for their properties.
The most widely available dietary source of EPA and DHA is cold-water oily fish, such as wild salmon, herring, mackerel, anchovies, and sardines. Oils from these fish have a profile of around seven times as much omega-3 oils as omega-6 oils.