Fish oil is extracted from the tissues of oily fish. Fish oil contains omega - 3 fatty acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Sardine fish oil contains around 20% of EPA and DHA. Crude fish oil has undesirable substances present in varying amounts. They are removed by processing and refining to increase their utility as starting materials for the manufacture of industrial products. Chemically modified fish oil is used in making industrial products such as protective coatings, leather chemicals, printing inks, lubricants and greases.