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Seasonal variation in prey consumption and food resource overlap was evident in an inland water body for mature male, mature female and immature inland silverside (Menidia beryllina). During the first growth phase marked by intensive somatic growth by immature inland silverside, few adults were present in the population (28% of total catch), thus minimizing intraspecific competition for food resources between juvenile and adult inland silverside. During the second growth phase by adults, few juvenile inland silverside were present (0% of total catch) in the population, again minimizing intraspecific competition for food resources between juvenile and adult inland silverside. A divergence in food resource overlap was observed when mature male, mature female and immature inland silverside were present in the population. These population-level demographic responses to energy acquisition are likely necessary to maximize individual growth of mature male, mature female and immature inland silverside resources unless there is differentiation in food resources. For the purpose of this study, the focus was on intraspecific partitioning of food resources by inland silverside because M. beryllina is the main obligate planktivore in the inland water body studied. Other studies have focused on interspecific competition of inland silverside with its congener Atlantic silverside (Menidia menidia) (Bengtson, 1982, 1984, 1985). In order to meet the energy demand of the two coinciding growth periods (first stage juvenile growth and second stage adult growth), partitioning of food resources is expected so that suitable energy is available to meet demands of the mature male, mature female, and immature inland silverside. The objective of this study was to characterize the food habits and measure the degree of food-resource overlap between mature male, mature female, and immature inland silverside throughout the breeding and growing seasons in an inland water body.