The current study aims to investigate the reproductive status and adaptive strategies of Coilia nasus in the Three Gorges Reservoir Region (TGRR). A total of 388 specimens were collected from the Wushan to Fuling section, which is the core area of the TGRR, between June and August 2021 to 2023. The analysis revealed that the current age structure of the C. nasus population is stable, with a female-to-male sex ratio of 0.92:1 in the spawning population. The youngest sexually mature individuals were 1 year old for both sexes. The females’ biological minimum size was 152.5 mm in body length and 11.96 g in body weight, while the males’ was 166.6 mm and 17.64 g, respectively. The average absolute fecundity and relative fecundity of C. nasus were (3.10±2.16)×104 eggs and (605.42±181.85) eggs/g, respectively. The egg diameter was (615.47±107.30) μm on average, and exhibited a unimodal distribution, which indicated a single spawning type. The average gonadosomatic index (GSI) was (6.32±4.52)% for females and (3.74±1.63)% for males, while the average hepatosomatic index (HSI) was (1.15±1.10)% for females and (0.63±0.53)% for males, respectively. Compared with the studies on C. nasus in the TGRR and other Yangtze River waters prior, the current spawning population in the TGRR tends to be shifting towards characteristics of an r-strategist, which is reducing egg size and increasing absolute fecundity. In conclusion, the stable population structure and size of C. nasus suggest that it has fully adapted to the environment of the TGRR. Its distribution range is likely to expand further into other upstream waters of the Yangtze River, including both the mainstem and its tributaries.