This study gives information on the feeding habits of 1,015 specimens, belonging to the five most abundant fish species in the Jacarepagua Lagoon, captured between March 1990 and February 1991, using trawl net. A feeding index was introduced to compare the relative importance of various food items, according to species standard length. A clustering analysis was calculated by using numerical coefficient of food items and defined two main groups: The 1 st represented by Xenomelaniris brasiliensis (Quoy & Gaimard, 1824) and Jenynsia lineata (Jenyns, 1842) considered omnivorous, fed mainly on insects, and the second including Tilapia rendalli (Boulenger, 1896), Phalloptychus januarius (Hensel, 1868) and Poecilia vivipara (Bloch & Schneider, 1801), whose principal diet source was epibenthic cyanophytes, specially Microcystis sp. and Lyngbia sp.