The population structure and reproductive biology of the surubim of Iguaçu, Steindachneridion melanodermatum, a large endemic and endangered catfish from Iguaçu River basin, were evaluated. In total, 182 specimens of this species were sampled from September 2010 to December 2016 in the Lower Iguaçu River, including some tributaries. The determination of the cycle and reproductive period was undertaken by assessing the mean variation in the values of the gonadosomatic index (GSI) of females and males, as well as by the frequency distribution of the stages of gonadal development on the basis of macroscopic and microscopic analyses. The total length and bodyweight ranged from 21 to 102 cm and from 82.8 to 15 670 g respectively. The reproductive period of this species was from June to September (winter and early spring), and may extend until November, with GSI peaking in August for males and September for females. The size at first maturation (L₅₀) corresponded to 39.5 cm for females and 43.9 cm for males. Spawning in this species was associated with lower water temperatures, and high discharge and dissolved oxygen concentration. Our findings are crucial in assisting the development of effective measures and specific criteria for the conservation of this endangered species.

伊瓜苏，黑僵硬皮担子的表面结构的种群结构和生殖生物学对伊瓜苏河流域的大型地方性和濒危cat鱼进行了评估。从2010年9月至2016年12月，在伊瓜苏河下游（包括一些支流）总共采样了182个该物种的标本。周期和生殖期的确定是通过评估雌性和雄性性腺体指数（GSI）值的平均变化，以及在宏观和微观基础上性腺发育阶段的频率分布来进行的。分析。总长度和体重分别为21至102厘米和82.8至15670克。该物种的生殖期是从六月到九月（冬季和初春），并且可能一直持续到十一月，男性的GSI在八月达到顶峰，而女性的GSI在九月达到顶峰。初熟时的大小（L ₅₀）对应于雌性39.5厘米，雄性43.9厘米。该物种的产卵与较低的水温，高排放和溶解氧浓度有关。我们的发现对于协助制定有效措施和保护这一濒危物种的具体标准至关重要。