Experimental studies on biomanipulation of silver carp and bighead carp in water resources management

An ecological project was put forward for the excess propagation control of zooplankton in water body by stocking silver carp or bighead carp. The biomanipulation of fish was experimentally investigated at stocking density of 30 g per cubic meter of water in the microcosms. The experimental results showed that the excess propagation of water flea could be effectively controlled and also the water quality was simultaneously improved by stocking silver carp or bighead carp especially poly-culture. During the experiment, the total nitrogen and total phosphorus were decreased to a certain extent, the content of organic matters was reduced and the level of dissolved oxygen was increased. In the microcosms of poly-culture, the phytoplankton, especially the biomass of blue and green algae, was controlled in a lower level. That controlled and deferred the appearance of eutrophication of water body.