This large species is distinguished by the following characters: robust, fusiform body, slightly compressed from side to side; total gill rakers on first gill arch 23-31; dorsal fins separated only by a narrow interspace, the second followed by 8-10 finlets; anal fin followed by 7-10 finlets; pectoral fins moderately long (22 to 31% of fork length) in large specimens (over 110 cm FL), but very long (as long as in Thunnus alalunga) in smaller specimens; 2 flaps (interpelvic process) between pelvic fins; very small scales on body; corselet of larger and thicker scales developed, but not very distinct; caudal peduncle very slender, with a strong lateral keel between 2 smaller keels; ventral surface of liver striated; swimbladder present. Colour of back metallic dark blue, lower sides and belly whitish; a lateral iridescent blue band runs along sides in live specimens; first dorsal fin deep yellow, second dorsal and anal fins light yellow, finlets bright yellow edged with black (Ref. 9684).