Extremely flattened side to side with a steep forehead and a mirror-bright flank, in small schools under bridges and around pilings.
To about 48 cm. Unmistakable in silhouette: extremely compressed and very deep, about half as deep as it is long, with a very steep, straight, angular head dropping to the mouth. Bright silver, with the front lobes of the dorsal and anal fins drawn out.
The Atlantic moonfish is the only real confusion and its head profile is rounded where this one is angular.
Juveniles are a different animal: greatly elongated black pelvic and dorsal spines, the second dorsal spine up to about two and a half times the length of the fish, a dark bar through the eye and four or five broken vertical bars.
One to ninety metres over shallow sand and hard bottom, in schools, small groups or pairs, feeding on crustaceans, small fish and worms. Juveniles are in estuaries and in the surf off beaches.
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.