Ploidy of hybrids between grass carp and bighead carp determined by morphological analysis

Twenty-six morphological and meristic characters of diploid and triploid hybrids between female grass carp, Ctenopharyngodon idella and bighead carp Hypophthalmichthys nobilis were analyzed by discriminant-function analysis. Twelve characters were useful in distinguishing between diploids and triploids. When these 12 characters were subjected to discriminant-function analysis, 97% of the hybrids were correctly classified as either diploid or triploid. No single character allowed diploids to be distinguished from triploids. Triploid hybrids had fewer morphological abnormalities than did diploid hybrids, possibly because triploid hybrids had two sets of chromosomes from the same species. © 1983 by the American fisheries society