The diet of the main fish species was evaluated from three stretches located in the Capivara reservoir, Paranapanema River and from one stretch on Tibagi River, the latter under the reservoir influence. The diet of these species, by the percentage composition, with the food items grouped was distinct: detritus and aquatic insects in three stretches (Cinzas, Cruzália and Porecatu); crustaceans and aquatic insects in Tibagi stretch. The fish species were grouped in six trophic groups, according to the main food items consumed determined by the Alimentary Index (IAi): carcinophagous, detritivore, herbivore, insectivore, omnivore and piscivore. All the six trophic categories have been identified among the fishes from the Tibagi stretch, five in Cinzas stretch, whereas four categories among fishes from Cruzália and Porecatu. The generalist/oportunist species Astyanax altiparanae, Moenkhausia intermedia and Pimelodus maculatus were included in diferent trophic categories according to the stretch. Plagioscion squamosissimus, piscivore in Porecatu and Cruzália, shifted to carcinophagy in the Tibagi and Cinzas stretches. The trophic structure and the abundance of the main fish species were different in each stretch, with the predominance of three species in each one, and always one of the introduced species figured among the three.
Paranapanema River basin; feeding fish; reservoirs; resources origin
