Fish oil is a common term used to refer to an oil composition, derived from fish, which is high in omega-3 fatty acids. Two of these being docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Fish oil works primarily through signalling molecules known as eicosanoids. These omega-3 fats are usually found in animal products, fish, and phytoplankton. Fish oil is generally used as a source of omega-3 fats as they are usually the cheapest and most common source of them.
They work well for me. Not much else to say.