Spanish: Atún de Aleta Negra
This small tuna has the typical fusiform, tuna body shape. The back is dark metallic blue, the sides are silvery-gray and the belly is white. Many have traces of a bronze-colored line down each side. The most reliable identifying characteristic is the color of the small finlets located behind the dorsal and anal fins. In the other four species of tuna, they are yellow or yellow, edged with black. In the blackfin, they are distinctly dusky, although they may have a yellowish tinge.
Blackfin Tuna ares the smallest tuna species in the Thunnus genus, generally growing to a maximum of 100 centimetres (39 in) in length and 21 kg (46 lbs).
Blackfin are only found in the western Atlantic from Cape Cod to Brazil.
This is a pelagic, schooling fish that generally feeds near the surface. Its diet consists of small fishes, squid, crustaceans, and plankton. An excellent light tackle species, it can be taken by trolling or casting small baits or lures, including ballyhoo, mullet and other small fishes as well as strip baits, spoons, feathers, jigs, or plugs; or by live bait fishing from boats at the surface of deep waters one to two miles offshore. It has some local commercial importance, but is predominantly an angler's fish. It is a spunky game species and the flesh is of good quality and flavor.