Abstract: This paper deals with the impact of the stocking density of silver carp(Hypophtyalmichthys moltrix) and big head carp(Aristichthys nobilis) on community structure of plankton in different fish ponds.The results indicate that the eutrophication of ponds is progressing after stocking silver carp and big head carp in shallow ponds(average depth 1.5～2.0 m).Accompanied with the increase of silver carp and big head carp,the utilization ratio of the primary production has been impmved and the standing crop of phytoplankton had not been decreased.On the contrary,the density of phytoplankton had increased.The individual size of phytoplankton and zooplankton had become smaller with the increase of stocking density of silver carp and big head carp. Meanwhile,the community structure of organism in water became more steady.Within suitable rang,the stocking density of silver carp and big head carp did not have significant inference on the diversity index of phytoplankton and zooplankton in intensive fish ponds. 

Key words: Hypophtyalmichthys moltrix, Aristichthys nobilis, plankton, fish ponds, stocking density, diversity index