Found in temperate marine waters throughout the world, tuna is a member of the mackerel family. It's probably the most popular fish used for canning today. There are numerous varieties of tuna, the best known being albacore, bluefin, yellowfin and bonito. All tunas have a distinctively rich-flavored flesh that is moderate to high in fat, firmly textured, flaky and tender. The high-fat albacore weighs in the 10- to 60-pound range, has the lightest flesh (white with a hint of pink) and is the only tuna that can be called "white. " Its mild flavor and prized white flesh make it the most expensive canned tuna. Yellowfin tunas (also called ahi) are usually larger than albacores, reaching up to 300 pounds. Their flesh is pale pink (it must be called "light"), with a flavor slightly stronger than that of the albacore. Among the largest tunas are the bluefin, which can weigh over 1,000 pounds. Young bluefins have a lighter flesh and are less strongly flavored, but as they grow into adulthood, their flesh turns dark red and their flavor becomes more pronounced. The small bonitos rarely exceed 25 pounds. They range from moderate- to high-fat and are the most strongly flavored of the tunas. Many Japanese dishes use dried bonito, called katsuobushi. Skipjack tunas (also known as Arctic bonito, oceanic bonito, watermelon and, in Hawaii, aku) get their name because they seem to "skip" out of the water. They can weigh up to 40 pounds, but are more typi-cally ranged from 6 to 8 pounds. Skipjack flesh is similar to that of yellowfin tuna. Depending on the variety, fresh tuna is available seasonally — generally starting in late spring and continuing into early fall. Frozen tuna is available year-round and is sold in both steaks and fillets. It may be cooked by almost any method including bak-ing, broiling, grilling and frying. Canned tuna is precooked and is sold as albacore (or white meat) and light meat. It comes in three grades, the best being solid or fancy (large pieces), followed by chunk (smaller pieces) and flaked or grated (bits and pieces). Canned tuna is packed in either water or oil — the latter containing far more calories. See also fish.