Abstract: The variety, quantity and biomass of various aquatic organisms in Gucheng lake of Nanuing had been investigated from June 1987 to July 1988. The fish production and stocking mass of rearing fish in the lake have been approximately calculated. It is concluded that if the quantity of fish increases to the maximum allowance (1.8 million fish) of the lake, fish production can be increased from present 750 tonnes to 1600 tonnes. In addition, this study can also provide a series of useful data for scientific managemant of Gucheng lake. The feasible suggestions about the ra tional utilization and protection of the resources in the lake are also proposed.