Phoxinus apollonicus is unequivocally distinguished from all other congeners by the reduced number of teeth on pharyngeal bones, usually four teeth on external row, but also 3 or 2, and 1 or 0 in the inner row. It also differs from other congeners by the combination of the following characters: the holotype has patches of breast scales connected anteriorly; the lateral line is nearly completed, posteriorly reaching the vertical line crossing the upper and the lower insertion of the caudal fin; flank of body with a marked mid-lateral longitudinal stripe extending from tip of snout to the base of caudal fin; a distinct spot at base of the caudal fin; a marked black spot on the opercular bone; depth of caudal peduncle, 2.2-2.8 times in its length and 1.8-2.5 in body depth; and eye diameter less than the preorbital distance(Ref. 105385).