Several aspects of growth and feeding of C. paludica have been assessed in two different environments: a lenitic and a lotic hydrosystem, Portil lagoon and Rivera de Cala river respectively. Growth patterns showed some differences with Iberian loach growing slower in the lagoon than in the river. Because of this, although individuals of both populations reach sexual maturity in their second year (year-class 1+), specimens of lagoon population mature at smaller sizes. The C. paludica population in the river showed a better somatic condition than in the lagoon. In both hydrosystems, their diet was mainly chironomid larvae and ostracods, although the Portil lagoon Iberian loach population showed a clear trophic segregation between young of the year (year-class 0+) and sexually matures individuals (year-class ≥ 1+).