48 species of fishes belonging to 15 family were collected and identified.Predominating among them are members of Cyprinidae, which comprise over 54% of the total number of species.From every aspect, ichthyofauna of Lake Taihu represent the typical one inhabiting stagnant water-bodies of the lower Changjiang(Yangtse) Valley.According to the survey of fish species made in 1950-1981, there were no less then 103 species in the lake.In 2002-2003, only 48 species were obtained from the lake.The cause of the diminution of fish species was chiefly that a partitive dike was built round the lake in the 1960s, thus severing the intercommunication between the Changjiang River and the Lake Taihu.The impoverishment of the submerged vagetion resource (such as the reclamation of land from the lake and fish-pen in the lake and so on ) also led to the diminution of species.On the other hand, the measures for conserving the fish resource and managements for increasing productivity of the lake are discussed.