Small to moderate-sized (up to ca. 60 cm, commonly to 10 cm), bottomorianted fishes. Body shape highly variable, but, typically, moderately elongate and more or less compressed posteriorly; no pored or tubed lateralline scales on body. Teeth typically conical (flattened and incisor-like in some genera), forming a single to several rows in each jaw; minute sensory papillae well developed on head (and few on body and caudal fin), forming transverse or longitudinal rows; five branchiostegal rays. Usually two dorsal fins, first one with 0-X flexible spines, second one usually with I spine and 5-66 soft rays; anal fin usually with I flexible spine and 5-65 soft rays; pectoral fin with 12-65 soft rays; dorsal- and anal-fin spines usually narrow and flexible; pelvic fins fused medially by frenum (between spines) and connecting membrane (between innermost rays), exclusive of several coral reef genera with separated ones; pelvic fin usually with I spine and 4-5 soft rays. Scales cycloid or ctenoid (with peripheral cteni only), minute to moderately large in size. Color: highly variable.|
Similar families occurring in the area. Blenniidae: single dorsal fin (may be deep notch developed between spinous and soft portions); teeth incisor-like, forming single row in each jaw; pelvic fins separated. Callionymidae: preopercle with a strong spine; no scales on body; gill opening restricted to a small dorsal or dorsolateral pore; pelvic fins separated. Eleotridae: pelvic fins separated; six branchiostegal rays. Platycephalidae: many short spines or bony tubercles on head; pelvic fins separated. Ptereleotridae: bottom-oriented, freeswimming fishes, with elongate (but not eel-like) and compressed body and separated pelvic-fins; mouth almost vertical in many species. Tripterygiidae: three dorsal fins; pelvic fins separated.
Remarks. Found in various habitats from torrential freshwater rivers to shelf waters (to depth of ca. 500 m), but most common in brackish waters and shallow coastal waters. Large species may be esteemed as food fish; several freshwater species may be treated as aquarium fish.