Behavioral and biochemical effects of fluoxetine on Poecilia reticulata: A relaxing state or an unapparent crisis?

Fluoxetine is an antidepressant used for the treatment of depression and anxiety disorders. We hypothesized that fluoxetine may positively influence the well-being of fish. We used Poecilia reticulata as a model organism and evaluated the behavioral, ecological and biochemical alterations following fluoxetine exposure at 0.05, 2.0, and 80 μg/L. For the behavioral analysis, we assessed swimming patterns, aggressiveness, social interactions and predatory behavior in a novel tank. Avoidance and colonization were evaluated as behavioral endpoints using the non-forced HeMHAS (Heterogeneous Multi-Habitat Assay System) as a novel approach to assess behavioral endpoints. The biochemical approach was based on the biotransformation enzyme activity (EROD and GST), anti-oxidative defense markers (GPx and GSH), oxidative damage indicators (LPO and DNA damage) and neurotoxicity (AChE activity). We found that the swimming patterns, aggressiveness and social behavior were reduced from 2 μg/L (p < 0.001) and the time spent by P. reticulata in the top and bottom areas differed significantly from 0.05 μg/L (p < 0.05). Additionally, organisms exposed to fluoxetine required more time (significantly from 2 μg/L; p < 0.001) to attack all the Daphnia sp. provided as prey. Further, in the colonization and avoidance tests, P. reticulata did not display colonization behavior (50–60 % time spent in the control compartment), and exhibited only weak avoidance responses, instead appearing to be either lethargic or in a relaxing state. The biochemical analysis showed that GST and LPO levels were elevated (p < 0.001), while both the GPx and GSH were reduced (p < 0.05).