The front spines of the fin are much taller than the rear spines, giving the fin a strongly curved, inward shape. The small structure between the pelvic fins is split into two points. The body is covered with very small scales. The pectoral fins are unusually long, reaching about 30% of the fish’s fork length in larger fish. The underside of the liver has visible grooves, and its central section is the largest. The body is torpedo-shaped, with a metallic blue-black back that gradually changes to silvery white on the underside.

It looks like Thunnus albacares (Yellowfin tuna) with a similar torpedo shape and are both highly migratory. However, they also have distinct differences in fin coloration and size, with albacore having notably long pectoral fins and yellowfin having a distinct yellow dorsal and anal fin.