Abstract: On the basis of fisheries resources investigations in 1992～1993 and in combing them with previous data in 1959 and 1982, the changes of fish species diversity and community structure diversity in Honghu Lake were analyzed. During the early years of blockage, the dominant fish species in Honghu Lake was lake-dwellers, and the river-lake migratory species and a few river-sea migratory species occupied certain amounts in catches. The dominants were the large and middle sized species, among which, the percentage of herbivorous species was 23%～35%, and carnivorous species around 10%～20%. In 1990s, the catches were dominated by Carassius orates, Pelteobagrus fulvidraco, Cultrichthys erythropterus and Hemiculter leucusculus, which were all small-sized ones. The majority in catches was omnivorous, and the herbivorous species almost disappeared in the lake. It was inferred that before the lake was blocked, there were over 100 fish species living in the lake, but the species reduced to about 50 species in 1990s, of which, only 30 or so could fulfill their life history in the closed lake environment. The species diversity indices and evenness were degraded to varying degrees.

Key words: Fish, Species, Community structure, Diversity, Honghu Lake