Population size structure can provide insights in species-specific knowledge and fish management. The purpose of the present study is to assess the influence of hydrological flow variability along the longitudinal gradient in the population size structure metrics of three non-native fish species widely distributed in the Iberian Peninsula. Alburnus alburnus L. Lepomis gibbosus L. https://www.nshomelesspets.com/product-category/popular-character-art/