A small, mottled-brown, moderately slender fish with a rounded tail fin, a rather blunt head and a terminal mouth. The top and sides of head are fully scaled. Upper lip is attached to the snout at its midline by a bridge of skin (frenum). All fins without spines. Lateral line absent. The dorsal fin is larger than the anal fin and located far back on the body, with the front of its base just behind bases of the pelvic fins.
Back and sides are dark brown with greenish reflections, the brown on sides interrupted by vertical pale zones, and with a narrow blackish bar at the base of the tail fin. Belly is buff-white. Fins are plain.
Unlike killifishes, mudminnows have the base of the dorsal fin well forward of the base of the anal fin, and they have a bridge of skin (a frenum) connecting the upper lip to the snout. Unlike young bowfins, mudminnows don’t have a lengthy dorsal fin, and have scales on the head.