Large pelagic predatory fish of the genus Thunnus and related genera, among the most commercially important fish worldwide. Tuna species are canned — skipjack and yellowfin dominating the canning trade — but tuna is also marketed fresh, smoked, and frozen, with bluefin commanding premium sushi prices. Nutritionally prized for high-quality protein and omega-3 fatty acids, tuna carries two classic safety concerns: histamine (scombroid) poisoning when temperature control fails after catch, and methylmercury bioaccumulation in large, long-lived specimens, which prompts consumption advisories for pregnant women and children.