Sometimes called bullet mackerel, the bullet tuna is a comparatively small and slender tuna. It has a triangular first dorsal fin, widely separated from the second dorsal fin, which, like the anal and pectoral fins, is relatively small. There are the usual finlets of the tuna. There is a small corselet of small scales around the pectoral region of the body.
Bullet tunas are blue-black on the back with a pattern of zig-zag dark markings on the upper hind body, and silver below. The fins are dark grey.