The upper Yangtze River supports many rare and endemic fish species and plays a critical role in biodiversity conservation in China. However, the fish fauna is under serious threat from large cascaded hydroelectric projects, including damming in Three Gorges, Xiangjiaba, and Xiluodu. The state of the endemic species is a major ecological concern. Estimates of population abundance and demography are needed for assessing fish population dynamics and effective fisheries management. A traditional method of estimating population parameters is based on the age-length relationship, which requires detailed age determination. A simpler alternative method is based on length-frequency data. We employed the second method and used the software FiSATⅡ (FAO-ICLARM Stock Assessment Tools) to estimate the growth rate and mortality of Rhinogobio cylindricus, an endemic species of the upper Yangtze River, based on a survey in the Zhuyangxi section conducted in 2007-2009, a period after the Three Gorges Reservoir was impounded, but before the Xiangjiaba and Xiluodu reservoirs were. Growth and mortality parameters of the fish were estimated based on length-frequency data. R. cylindricus ranged from 69.0 to 268.0 mm in length and 3.9 to 230.4 g in weight, with an average length of (181.4±26.9) mm and an average weight of (78.5±33.0) g. The length group of 125.0-225.0 mm dominated the catches (93.0% of the total number). The length-weight relationship was well fitted with a power function, W = 1.58 × 10^-5 L^2.95 (R² = 0.94, P < 0.01, n = 401), a result that means that the growth of the fish is isometric and adequately described by the Von Bertalanffy growth equation. Three growth-related population parameters, L_∞, k, and t₀, were estimated as 361 mm, 0.21 a^-1, and -0.68, respectively. The three mortality-related parameters, Z, M, and F, were estimated as 1.70, 0.50, and 1.20, respectively. The minimum catchable size was 163.4 mm, and the exploitation rate observed was 0.70, higher than the estimated optimum exploitation rate (0.60), but lower than the maximum exploitation rate (0.75). The annual yield of R. cylindricus in Zhuyangxi section was 6716 ind. (0.50 t) in 2007, 22772 ind. (1.87 t) in 2008, and 16139 ind. (1.20 t) in 2009, with an average of 15209 ind. (1.19 t). Population abundance was estimated by applying Length-structured Virtual Population Analysis to length-frequency and annual yield data. The estimated annual-average abundance of R. cylindricus in Zhuyangxi was 16361 ind./km (1.25 t/km) in 2007, 13922 ind./km (1.74 t/km) in 2008, and 26836 ind./km (1.93 t/km) in 2009, respectively, with an average of 19040 ind./km (1.64 t/km). The estimated growth-related population parameters of R. cylindricus by length-frequency data in this study are consistent with previous studies based on age-length data, which indicates that the result is reliable. Considering the current high exploitation rate for R. cylindricus, we recommend a minimum catchable length of 193.5 mm to decrease its exploitation rate. We further suggest that management authorities establish a closed period for fishing and assist commercial fishermen with alternative career options to reduce harvesting pressure on the endemic species.