Eyes as a Novel Target of Psychoactive Contaminants in Fish

Psychoactive drugs are prevalent aquatic contaminants that target neurotransmitter systems conserved across vertebrates. While their effects on fish brain chemistry and behavior are increasingly recognized, impacts on sensory systems such as vision remain largely unexamined. Here, we demonstrate that environmentally relevant mixtures of psychoactive drugs accumulate in the eyes of European perch (Perca fluviatilis) under both laboratory and field conditions, often at higher concentrations than in the brain. This ocular accumulation significantly alters neurotransmitter levels critical to visual processing. Our findings reveal a previously overlooked mechanism of sensory disruption with potential consequences for fish behavior, ecological interactions, and population fitness. Current environmental risk assessments, which rarely consider the visual system, may therefore underestimate the ecological impact of pharmaceutical pollution. These results underscore the need to expand ecotoxicological frameworks to include sensory endpoints and visual function as sensitive indicators of contaminant exposure in aquatic organisms.