A slender green-backed jack that schools in tight numbers over eastern Pacific reef.
To about 55 cm on the confirmed figure, though one source gives 70 and there are unconfirmed reports of metre-long fish. Relatively slender for a jack, olive to dark bluish-green above and silvery-grey to golden below, with a black blotch on the gill cover, often with a pearly white mark beside it in schooling fish. Juveniles carry about seven dark bars.
The identification, if you have the fish in hand, is the scute count along the tail base: forty-two to fifty-six, which is the highest of any jack on this site and far above anything it could be confused with.
Nought to a hundred metres over the shelf, on soft bottoms, inshore reefs, bays, estuaries and lagoons. It is gregarious and forms moderately large schools, feeding mainly on silvery fish and also squid and shrimp. Juveniles shoal into shallow bays and estuaries.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.