Genetic population structures of Protosalanx chinensis , Neosalanx taihuensis , and N .oligodontis in Lake Taihu were assayed using RAPD method .P .chinenesis and N .taihuensis were collected in six regions throughout the whole lake , and N .oligodontis was collected in two of the six regions.Results demonstrated that these three Salangid fishes did not reveal any structural differentiation .Genetic similarity indices suggested that P .chinensis has to lost genetic variation a greater degree because in history it suffered a greater loss in population quantity than N .taihuensis and N .oligodontis resulted from fishing pressure , while N .taihuensis and N .oligodontis have maintained somewhat larger genetic variation .