The dietary regime of detritivorous fish from the River Jacare Pepira, Brazil

The diet of detritivorous fish was analysed at four distinct habitats in a tropical river during the wet and dry seasons. Two methodologies were used to determine the diet of the fish: (1) the direct analysis of the stomach c ontents; and (2) the use of stable carbon isotopes. Both methods indicated food partitioning among the fish. The stomach contents showed what the fish had ingested when captured and the C-13 isotope indicated what it had assi milated over a long period of time. The C-13 isotope suggested the existenc e of sectional differences in the feeding of the detritivorous fish along t he river. Plants employing the C-4 photosynthesis pathways seem to have lit tle influence on the diet of these fish. This method proved to be more appr opriate for the detection of the main food sources of the captured fish.