Back and upper sides are dark blue to black with a gray or green iridescence. The lower sides are silvery, marked with gray spots and bands. 2 nd dorsal fin reddish-brown. Anal fin dusky with some yellow. Finlets are yellow, edged with black.
Caudal keel is black at adult stage, but is semi-transparent when immature.
Found in western Atlantic along Labrador and Newfoundland, southward to Tobago, Trinidad, Venezuela, and the Brazilian Coast. Distribution in east Atlantic extends as far north as Norway and Iceland, and as far south as northern West Africa. Finlets are uniformly dusky with only a trace of yellow, not bright lemon yellow like other tunas, and may have white edges. Back is bluish-black, sides are silvery grey, belly is milky white. Gill rakers are fewer in number than in other species of Thunnus , with 19-25 on the first gill arch.