juvenile: white bars - all solid, on rear body only
C: no white border
23-31 gill rakers
pectoral: long (not past D2 in adult), tip curves down
Thunnus obesus (Lowe, 1839)
Body elongate, fusiform, deep, deepest under center of first dorsal base, moderately compressed; eye large; no fatty eyelid; teeth slender, conical; top of tongue with 2 cartilaginous ridges; 23-31 gill rakers; 2 dorsal fins barely separated; 1st dorsal XIII-XV; 8-9 finlets after dorsal and anal fins; pectoral fins moderately long, in fish ~ 110 cm tip is pointed down and fin reaches past 2nd dorsal; short, forked bony process between pelvic fins; two small keels separated by large keel on tail base; well developed scaly corselet on front of body; small scales cover body behind corselet.
Back metallic dark blue, lower sides and belly whitish; a lateral iridescent blue band running along sides of live fish; fish to 110 cm with wide, continuous white bars on rear half of body, larger fish without bars; first dorsal fin yellow; second dorsal and anal fins pale yellow; finlets bright yellow, edged with black; tail dark grey, no white rear border.
Maximum size, 250 cm; all-tackle world record 197.2 Kg.
Habitat: oceanic pelagic.
Depth: 0-1500 m.
Circumglobal in tropical and temperate seas; southern California to the mouth of the Gulf of California to Chile and the oceanic islands.