Tuna is a fish rich in protein, fatty acids, and a complex of vitamins and minerals. It is low in calories and is considered a dietary product. In appearance and taste, the fish resembles meat, which is why tuna is sometimes called “veal of the sea.” Tuna can be bought all year round, but the freshest fish is sold during the fishing period from May to early September. Tuna can most often be found on sale in fillet form. It dries quickly, so fish should be cooked immediately after purchase.