Body an elongate oval (depth 40-45% of SL); lower profile of head distinctively concave; mouth highly extensible, pointing downward when protruded; lower border of preopercle smooth; bone under front of eye with smooth border; teeth inside throat all pointed; dorsal rays IX,10, elevated at front, 2nd spine less than or equal to distance between tip of snout and rear of eye; anal fin III, 7, 2nd spine short, < height of tail base; pectoral fin pointed, not reaching to origin of anal fin; tail fin deeply forked; scales large, conspicuous and finely rough, covering most of head and body; dorsal and anal fins fold into a high scaly sheath along their bases; scales extend before front of eye on top of snout around scaleless groove; lateral-line scales 44- 48.
Overall silvery white; spiny dorsal fin with grey base, white center, wide black tip.
Size: reaches at least 21 cm.
Inhabits sand and mud bottoms of bays and estuaries; also venture as much as 20 Km up rivers.
Depth: 0-30 m?
California to the Gulf of California to northern Peru, the Galapagos and Cocos.