The body is ovoid, flat on the side, and there are serrated scales on the abdominal edge; Big head, short and blunt kiss; The lateral position of the eyes has developed fat eyelids. Sub-mouth position, slightly straight; Toothless; The upper jaw protrudes slightly from the lower collar, and the end of the upper jaw bends downward and extends backward below the front edge. The gill cover is smooth; There is deltoid muscle above the lower branch of the anterior branchial lid. The body has oval scales, the rear edge of the scales is serrate, and the caudal fin is deeply forked. The back is green and brown, and the lower body and abdomen are silvery white.
Small and medium-sized fish migrating along the upper and middle layers of offshore sometimes enter estuaries, downstream brackish rivers, inner bays or lagoons to lay eggs. Group travel. Feeding on plankton.