21a. (From 20a.) Eye large, diameter (A) equal to or slightly greater than length of snout (B); red to red-orange pigment in eye and at base of caudal fin above and below dark caudal spot. Barbel sometimes present in corner of mouth.
redeye chub
Notropis harperi

21b. (From 20a.) Eye small, diameter (A) less than lendth of snout (B); red pigment absent from eye and base of caudal fin. Barbel present in corner of mouth.
Genus Hybopsis