For the purpose of fishery development, a hydrobiological investigation of Lake Chenhu was carried out in 1983 with reference to the productivity of various food organisms as well as fish. Of the entire lake, the annual net primary production was determined to be 27,818 ×106 kcal for phytoplankton, 2,898×106 kcal for macrophytes and 64,840×106 kcal for wet land vegetation. The annual secondary production chiefly from gastropods was 2,632×106 kcal. On the basis of 1981?982 fishery data, the production of the main stocked fishes in the lake was also roughly computed. Analysing all obtained production data, we find the energy conversion rate of food organisms to fish in the water at the present stage is fairly low. Even in 1982, the year of better fishery management, food energy converted to plankton feeders or herbivores was only 1.6-1.8%; energy converted to fish yield was even lower, only 0.2?.8%. To get a potential fish output of the ecosystem, a tentative estimation of fishery capacity of Lake Che For the purpose of fishery development, a hydrobiological investigation of Lake Chenhu was carried out in 1983 with reference to the productivity of various food organisms as well as fish. Of the entire lake, the annual net primary production was determined to be 27,818 × 106 kcal for phytoplankton, 2,898 x 106 kcal for macrophytes and 64,840 x 106 kcal for wet land vegetation. The annual secondary production chiefly from gastropods was 2,632 x 106 kcal. On the basis of 1981? 982 fishery data, the production of the main stocked fishes in the lake was also roughly computed. we found the energy conversion rate of food organisms to fish in the water at the present stage is fairly low. Even in 1982, the year of better fishery management, food energy converted to plankton feeders or herbivores was only 1.6-1.8%; energy converted to fish yield was even lower, only 0.2 ~ .8%. To get a potential fish output of the ecosystem, a tentative estimation of fishery ca pacity of Lake Che