Abstract: The results of polymorphic study on the electrophoretic patterns of laotate dehydrogenase and esterase isozymes in the sperms, mature eggs, ten embryonic and postembryonic samples taken from two breeding populations of silver carp (Hypophthalmicthys molitrix) are given in this paper. On molecular biological basis of the polymorphism, we discuss the regulation of gene expression, the morphogenetic stimulus, and the mode and relative metabolic rate for establishing special cytophysiological functions. In short, the general developmental genetic rule of this fish are the same as other teleost fishes studied previously. We designate these population differences of isozymic ontogenesis as "ontogenetic polymorphism" which is not vital to the development of silver carp, so that it belongs to a kind of common biochemical polymorphism. In this essay, the related problems ought to be further studied and their prospects for fishery use are also mentioned.