Meristics and Morphometrics of Golden Shiner,Notemigonus crysoleucas,Rudd, Scardinus erythrophthalmus,and Their Reciprocal F1 Hybrids

Rudd, Scardinus erythrophthalmus, a European minnow, has been hybridized with golden shiner, Notemigonus crysoleucas, in an attempt to produce sterile hybrids. If these hybrids are to be used as bait, easy means of differentiating the parental species and their hybrids is needed to ensure that no rudd are being sold. The scale pattern along the keel is the easiest and quickest way to distinguish the two species and their hybrids: the keel is raised and scaleless in the golden shiner, and it has 6-9 scales in the rudd; in hybrids, the keel is scaled, but the scales have different shapes and insertions than those in the rudd. No other phenotype can be used to positively identify these groups. No phenotype can be used to separate the reciprocal hybrids.