Abstract: The Changshuhu Reservoir is situated on the Longchi River,about 15 kilometres from the city of Changshu in Szechwari Province.It was filled in 1955,and covers an area of about 6,000 hectares. A biological survey was made in May and in October 1958.Data concerning the water-analyses,phytoplankton,zooplankton,and fish fauna are dealt with in the present report. Some points of particular interest in the development of this reservoir may be summarized:1) Conditions in the reservoir are evolving naturally,with little artificial interference;2)the plankton is beginning to increase,both in variety and quantity;3) the aquatic vegetation and benthos remain poor;4) the fish fauna has not changed much in composition,but the populations of Hemiculter. Carassius,and Opsariichthys have obviously increased markedly. Suggestions regarding the management of the fisheries are made.