To assess the early-stage effectiveness of the "ten-year fishing ban" policy， this study took Lake Gehu， a typical shallow lake in the middle and lower reaches of the Yangtze River， as the research subject， systematically analyzing the spatiotemporal variation characteristics of its fish community structure and the key influencing factors. Based on quarterly survey data from 2023， this study analyzed the fish species composition， dominant species， and ecological types. The Shannon-Wiener diversity index， Pielou evenness index， and Margalef richness index were employed to assess community diversity. Non-metric multidimensional scaling （NMDS） was used to examine spatiotemporal differences in community structure. Building on this， similarity percentage analysis （SIMPER） was applied to identify the key species contributing to differences among lake regions. The abundance-biomass comparison （ABC） curves were utilized to evaluate community stability. Finally， Mantel tests and redundancy analysis （RDA） were conducted to explore the relationships between fish communities and environmental factors. A total of 53 fish species were collected， belonging to 8 orders， 13 families， and 40 genera， with resident， omnivorous， and mid-lower water layer species being dominant. The dominant species were Aristichthys nobilis， Coilia nasus， Hypophthalmichthys molitrix， and Culter dabryi. The mean values of the Shannon-Wiener index， Pielou’s evenness index， and Margalef’s richness index were 3.96， 0.32， and 2.13， respectively. NMDS results showed no significant seasonal differences in fish community structure， but significant spatial differences （P<0.05）. SIMPER analysis further indicated that ten species， including C. nasus， Pelteobagrus nitidus， C. dabryi， and A. nobilis， were the main contributors to inter-regional differences. Spatially， both diversity indices and community stability were significantly higher in protected areas than in non-protected areas. Seasonally， both exhibited a consistent trend： spring > summer > winter > autumn. Water temperature， water depth， total phosphorus， and dissolved oxygen were identified as key environmental factors influencing community structure. During the early stage of the ten-year fishing ban， the fish community in Lake Gehu showed signs of recovery， yet the recovery effects exhibited spatial heterogeneity， with the protected area demonstrating significantly better restoration than other lake regions. This study can provide baseline data for evaluating the early ecological effects of the Yangtze River "ten-year fishing ban" in shallow lakes， and offer scientific references for fisheries resource management and biodiversity conservation in Lake Gehu and other lakes subject to fishing bans.