Lake Baima, located at the lower reaches of the Huaihe River Basin, serves as a multi-functional water body with roles in flood retention, water supply, ecological balance, cultural landscape, tourism, and aquaculture. To assess the fish community structure and diversity during the initial phase of the fishing ban, a survey of fish resources was conducted from June 2023 to April 2024. During the studied period,Pseudobrama simoni, Aristichthys nobilis, Acheilognathus macropterus and Culterichthys erythropterus were identified as the dominant species, whileCoilia brachygnathus ,Culter dabryi ,Toxabramis swinhonis ,Hypophthalmichthys molitrix ,Carassius auratusandCyprinus carpioexhibited seasonal dominance. The Margalef richness index, Shannon-Wiener diversity index, Pielou evenness index and Simpson’s diversity index for the fish community were 4.860, 2.424, 0.637 and 0.844, respectively. Although there were no significant differences in fish species diversity across various lake regions and seasons, Bray-Curtis cluster analysis and non-metric multi-dimensional scaling (NMDS) showed that there were distinct spatial and temporal variations in fish community structure. At the similarity level of 52.28%, the fish communities were categorized into three groups, i.e. , the central and northern lake areas (group Ⅰ), the spring, summer and autumn seasons in the southern lake area (group Ⅱ), and the winter season in the southern lake area (group Ⅲ). The stability of the fish community in the northern lake area exhibited considerable fluctuations, whereas the community structure in other regions of Lake Baima was relatively stable. These findings suggested a recovery trend of the fish resources in Lake Baima. However, there were considerable challenges including the high proportion of small omnivorous fish, low abundance of protected species, and low stability of fish community in the northern lake area. It was recommended to enhance the conservation for Lake Baima’s fish resources through targeted actions such as stock enhancement, habitat restoration, pollution source control, and strengthened fishery regulation, as well as regular monitoring. The results of this study provided essential data for evaluating the long-term effects of the ten-year fishing ban in Lake Baima, and offered a scientific foundation for the management and conservation of fishery resources in other fishing banned lakes.