Genus: Butis, Mud Sleeper, Flathead Gudgeons

BUTIS

FLATHEAD GUDGEONS

Elongate; head rounded; a serrated bony ridge over each eye; front nostril a short tube; lower edge of gill opening extends forward to below eye; no downpointing spine on preopercle; gill membranes broadly joined to throat, with 6 rays; dorsal fin VI + I, 8, base of 2nd dorsal < distance from the end of that base to tail fin;  anal fin I, 7-8; pectoral fin 19-22, rays branched; pelvic fins I, 5, completely separate; segmented tail fin rays 17; body scales rough; lateral scales 25-33; top of head, cheeks and operculum scaled, no enlarged scale between eyes; no lateral line.

A tropical Indo-Pacific estuarine genus with 6 species; one introduced, apparently from the Indo-W Pacific in a ship’s ballast water, to the Pacific entrance to the Panama Canal and to Venezuela.