This paper reports the xesults infrom the fermented marsh-gas pondusing pig farmyard manure and manuxe waterrzs fertilizers for raising phytoplankton.experiment w as carried nut in two same siaed neightouring fish ponds in 1980---1982. Some physical-chemical environment and biological factors had been measured and analysed. The marsh-gas water manifests great effect on change of the constitu-eats of phytoplankton，and it can also regulate and sustain the natural food in different seasons. Consequently, a good harvest wo}xld be expected. The net yield per Mu is 564.5 Kg in 1981，and 655.5 Kg in 1982. Since the marsh gas-manure has long runfertility in compare with pig farmyard manure. So the it is a good fertilizer for high vield fish founds.