Psychiatric drugs have been increasingly prescribed, leading to an increase in their concentration in aquatic ecosystems due to the inefficient removal in urban waste water. Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) and is detected at concentrations ranging from ng/L to µg/L, producing potentially harmful effects in non-target organisms. Studies have suggested that low concentrations of these pharmaceuticals could provoke effects at neuronal level only detected by sensitive endpoints such as behavior. Thus, this work aims to evaluate the effects of fluoxetine on behavior of adult zebrafish (Danio rerio) when subject to a chronic exposure (21 days) to concentrations of 1000, 100, 10 and 1 ng/L plus control. Behavioral tests were performed to assess anxiety-like behavior (locomotor activity, thigmotaxis and novel tank diving test). The results obtained showed that the concentrations used did not affect the locomotor activity and thigmotactic behavior. In the novel tank diving test, fish exposed to the highest concentration (1 µg/L) showed a longer permanence in the bottom of the aquarium. However, this result was not statistically significant.

Based on these results, we can conclude that fluoxetine, at environmentally relevant concentrations, did not alter the behavior of adult zebrafish.