Key to the Species of Cyprinidae

10a. (From 9a.) Anal fin rays usually 7; leading rudimentary ray of dorsal fin stout, with blunt tip, and separated from first principal ray by narrow membrane; lateral line relatively straight, not deflected downward anterior to anal fin; head of breeding of male with tubercles only on snout.
Genus Pimephales

10b. (From 9a.) Anal fin rays usually 10 to 13; leading rudimentary ray of dorsal fin slender and not widely separated from first principal ray by membrane; lateral line deflected downward anterior to anal fin; tubercles on head of breeding male not restricted to snout.
Genus Lythrurus