Diet and dietary overlap of three sympatric fish species in lakes of the Upper Parana River floodplain

For a dietary study, specimens of Astyanax bimaculatus, Astyanax schubarti, and Moenkhausia intermedia were caught monthly with seines-nets in six lak es (Pau Veio, Porto Rico, Tres Amigos, Mutum, Pontal, and Canal do Meio), o n the floodplain of the Upper Parana River, from March 1992 through Februar y 1993. We analyzed stomach contents of 599 A. bimaculatus, 293 A. schubart i, and 394 M. intermedia, by the Occurrence and Points methods, combined in the Alimentary Index (AI). This analysis revealed that these species have broad dietary spectra, A. bimaculatus was an omnivore, with a tendency towa rd herbivory-insectivory. In most of the lakes it consumed terrestrial inse cts, followed by higher plants and microcrustaceans, A. schubarti was an om nivore, consuming the same type of items in the different lakes, in differe nt proportions depending on the locality. M, intermedia was a planktophage, feeding mainly on cladocerans (more than 50%) in all the lakes except for Pontal, where higher plants were predominant (45.1%). Although A. bimaculat us and A. schubarti consumed similar items in the different localities, det rended correspondence analysis (DCA) showed distinct segregation among the three species in all lakes studied.