Pharmaceutical residues are increasingly detected in environmental and biological samples, some at levels known to adversely affect non-target organisms; however, less is known of how these organism-level effects relate to the ecology of aquatic systems. Foraging processes may be used as behavioral endpoints that link effects on individuals to the population and community levels, enabling risk assessment of environmental contaminants at larger ecological scales. In this study, we performed feeding trials using juvenile Eurasian perch (Perca fluviatilis) exposed to the selective serotonin reuptake inhibitor (SSRI) sertraline to test the hypothesis that sertraline alters foraging ecology of the fish in terms of their functional response. We found an exposure-dependent decrease in feeding with increasing sertraline concentrations. Further experiments revealed that feeding rates decrease at both low and high prey densities, indicating effects on both attack rate and handling time, respectively. Because the functional response can shape consumer-resource dynamics, such effects may alter the stability of predator-prey systems and consequently, community structure.