The present work was conducted at Andorinha stream, oriental slope of Ilha Grande, and aimed the analysis about the correlation between allochthonous preys input and the use of such preys as food resource for Bryconamericus microcephalus (Miranda-Ribeiro, 1908). Quantification of imported preys was done during May/2002 and February/2003 together with fish samples used for diet analysis. Feeding selectivity was established for Young and adult individuals according to prey size and taxonomical order. Ivlev Electivity Index (IEI) was applied for the abundance of consumed preys and their environmental availability. Homoptera (IEI = 0,94), Coleoptera (IEI = 0,57) and Diptera (IEI = 0,50) were preferred among adult individuals while Hemiptera (0,98), Diptera (0,60) and Homoptera (0,98) preferred among young individuals. Despite their high environmental availability Hymenoptera (IEI = -0,15; -0,42) and Orthoptera (IEI = -0,52; -1) were rejected among adult and young individuals, respectively, suggesting that they were eaten because their abundance. These results indicated that young and adult individuals of B. microcephalus presented quite different feeding preferences.
Diet; selectivity; Rain Forest
