We examined the responses of zooplankton community, water transparency, chlorophyll a-and nutrients to manipulation of density of silver carp (Hypophthyalmichthys rnolitrix) in an one-way factorial experiment using enclosures placed in Donghu (East Lake, 30" 33' N, 114" 23' E), located in Wuhan, P. R. China. Enclosures (18.75 m3) were treated with four silver carp densities, 0,81,225,485 g/m2. Total zooplankton abundance (excluding nauplii and rotifers except for Asplanchna sp.) and the mean size of dominant cladoceran species were significantly greater in enclosures with 0 and 81 fish densities than those in enclosures with 225 and 485 fish densities. Water transparency also improved significantly when silver carp densities were 0 or 81 g/m2. We did not find significant effects of silver carp density on chlorophyll a, total phosphorus, or total nitrogen concentrations.We conclude that by reducing planktivorous fish to below the current density (190 g/m'), the zooplankton community can be shifted from the dominance of small-bodied Moina sp. to dominance of large-bodied Daphnia sp. Further, the water clarity can be increased. INTRODUCTIONA recent survey reported that the proportion of lakes that can be classified as eutrophic (total phosphorus ranging from 0.01 8 to 0.97 mg/L) in China has increased from 5% to 55% in the past decade (Jin 1994). Water transparency of less than 1 m and reduced