The little tunny has a robust, torpedo-shaped body built for powerful swimming. The mouth is large, slightly curved, and terminal with rigid jaws. The lower jaw slightly protruding past the upper jaw. There are two longitudinal ridges on the tongue. Scales are lacking on the body except for the corselet and the lateral line. The corselet is a band of large, thick scales forming a circle around the body behind the head, extending backwards along the lateral line. The lateral line is slightly undulate with a slight arch below the front of the dorsal fin, then straight to the caudal keel. The caudal fin is deeply lunate, with a slender caudal penduncle including one short keel on each side. The first dorsal fin has high anterior spines giving the fin a concave outline, separated only narrowly from the second dorsal. Pectoral fins are pointed and short, not reaching to the end of the first dorsal; the pelvic fins are inserted just behind the origin of the pectoral fins. Swimbladder is absent. This fish is steel blue with 3-5 broken, dark wavy lines, not extending below the lateral line. The belly is white and lacks stripes. There are 3-7 dark spots between the pelvic and pectoral fins. Spots below the pectoral fin are dusky.