Silver carp (Hypophthalmichthys molitrix), grass carp (Ctenopharyngodon piceus), bighead carp (Aristichthys nobilis), and black carp (Mylopharyngodon piceus) rank first, second, fourth, and seventh in world fish production. In China, the Yangtze River harbours the most important natural populations of these species. We performed a polymerase chain reaction restriction fragment length poymorph...