By Koichi Shibukawa

Butis butis

Butis koilomatodon

Ophiocara porocephala

Small to moderate sized fishes (up to ca. 85 cm, commonly to 20 cm), bottom-oriented fishes. Body moderately elongate, more or less compressed posteriorly; no pored or tubed lateral-line scales on body. Teeth usually conical, forming some or more rows in each jaw; sensory-papillae rows well developed on head (and few on body and caudal fin); branchiostegals 6. Two dorsal fins, first one with VI-X flexible spines, second one with I spine and 6-12 soft rays; pelvic fins separated, innermost or preceding rays longest; pelvic fin usually with I spine and 5 soft rays. Color: highly variable, typically blackish or grayish brown with dusky mottles, whereas some species has brilliant color with e.g., bright yellow and/or red spots.

Similar families occurring in the area. Blenniidae: single dorsal fin (sometimes deep notch developed between spinous and soft portions); teeth incisor-like, forming single row in each jaw. Callionymidae: preopercle with a strong spine; no scales on body; gill opening restricted to a small dorsal or dorsolateral pore; no spines on second dorsal and anal fins. Gobiidae: pelvic fins fused medially one another in many species; five branchiostegal rays. Platycephalidae: many short spines or bony tubercles on head; no spines on second dorsal and anal fins. Ptereleotridae: bottom-oriented, freeswimming fishes, with elongate (but not eel-like) and compressed head and body; five branchiostegal rays; mouth almost vertical in many species. Tripterygiidae: three dorsal fins.

Remarks. Typically found in fresh and brackish waters, whereas some found in coral reefs. Carnivorous. Large species often esteemed as food fish; some freshwater colorful species often treated as aquarium fish.