The river-lake transitional zone of Poyang Lake is a key water area connecting the Yangtze River and Poyang Lake. It is important to understand the relationship between fish communities, hydrological dynamics, and other water environment factors in these waters. This study examined the status of fish resources in the river-lake transitional zone of Poyang Lake, from 2021 to 2022. We collected 3,880 individual fish, belonging to 5 orders, 10 families, and 54 species. Cypriniformes comprised the largest number of fish species at 64.81% of the total number of species. Overall, the fish ecological types were dominated by carnivorous, demersal, resident and viscous egg fish. According to the relative importance index, there were eight dominant species (including Coilia brachygnathus and Megalobrama mantschuricus). The fish community was more abundant and structure was more complex in downstream areas and in the flood season. This area showed significant regional differences in the fish community structure, whereas seasonal differences were not significant. Analysis showed that the water level and flow correlated significantly with the Margalef richness index and Shannon-Wiener diversity index. Redundancy analysis showed that pH, oxidation-reduction potential, dissolved oxygen and the water level were key environmental factors affecting the fish community structure and species spatio temporal distribution. Thus, high water levels in the flood season and in downstream waters are important to the river-lake transitional zone of Poyang Lake. Collectively, this survey of fish resources in the river-lake transitional zone will support the protection and management of aquatic biological resources in Poyang Lake.