The feeding dynamics of juvenile largemouth bass (Micropterus salmoides) were studied from March 1992 to December 1994 in Lucchetti Reservoir, Puerto Rico. Early piscivory by juvenile bass was aided by constant, but qualitatively variable, availability of fish prey items including threadfin shad (Dorosoma petenense), mozambique tilapia (Tilapia mossambica), redbreast tilapia (T. rendalli), and bluegills (Lepomis macrochirus). Threadfin shad was the primary food item for juvenile bass, supplemented by bluegills and tilapias when abundant. Insectivory was high in situations of low fish prey abundance and was accompanied by an increased occurrence of empty stomachs. Two temporal sub-cohorts (early and late) showed different food utilization. Insect consumption by early-hatched bass in Lucchetti Reservoir was consistently higher than for late-hatched bass; piscivory was lower for early-hatched bass than for late-hatched bass. Despite the artificial predator-prey community comprised of exotics, juvenile largemouth bass generally experienced adequate food supplies and rapid growth.