Small to medium sized marine and brackish fishes.
Body slimy and deep, ovate, strongly compressed, except a few species; head usually naked with bony ridges on upper surface; a median bony ridge (crest) on nape; scales small cycloid, easily shed; gill membranes united with isthmus; mouth small, highly protrusible; no pseudo-branchiae; unique light organ encircling the posterior part of esophagus.
A single dorsal fin, lacking a distinct notch, with VII-IX spines (usually VIII) and 14-17 soft rays; anal fin usually with III spines and 13-14 soft rays; pelvic fin I, 5; caudal fin forked; vertebrae 22-24.