The gray correlativity analysis was applied to study on the relationships among fishes in high yield poly culture pond. The results are as follows: the relation between the input of mud carp fingerlings and output of big head carps is the biggest( R =0.7921), and the relation between the input of grass carp fingerlings and output of mud carp is the second ( R =0.7415).The input mud carp fingerlings becomes superiority maternal factor, the output of big head carps becomes superiority junior factor. T...