Fish oil comes from the tissues of oily fish. The best sources are cold-water, fatty fish. When it comes to human consumption of fish oil, you can get it from fish themselves or from a fish oil supplement.
Fish oil is a concentrated source of omega-3 fats, which are also called ω-3 fatty acids or n-3 fatty acids. To get more scientific, omega-3s are polyunsaturated fatty acids, or PUFAs. Our bodies are able to make most of the fats we need need, but that’s not true for omega-3 fatty acids. When it comes to these essential fats, we need to get them from omega-3 foods or supplements.