Blue-backed fish (背の青い魚 se no aoi sakana);also referred to asBlue-fish (青魚 aozakana)is a category of fish used in Japanese cuisine that have a rich and fatty taste, and are distinguished from another category of white meat fish that tend to have a lighter and more delicate flavor. It is not a scientific categorization, but refers to commonness in outer appearance, fleshiness and oiliness and include such species of fish as sardine, mackerel, herring, perch and anchovy. Blue-backed fish tend to be high in the essential amino acid, histidine, as well as the omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and are generally said to have health benefits when included in a balanced diet, including such effects as reducing cholesterol.