Owens pupfish is a small, deep-bodied, laterally compressed fish with a total length that rarely exceeds 6 cm (2.5 in). Females are dusky, olive-green in color, with several dark vertical bars aligned in a row along the sides. Males are bright blue, particularly during the spring and summer spawning season. This species is distinguished from other pupfishes by the anterior placement of the dorsal fin, long caudal peduncle (the narrow part of a fish’s body to which the caudal or tail fin is attached), absence of spine-like projections on scale circuli (growth rings), and absence of a terminal black band on the caudal fin. Owens pupfish also have a greater number of dorsal, pelvic, pectoral, and anal fin rays than other pupfish species.