Asian Journal of Research in Biosciences

Toxicology examines the harmful effects of substances on biological systems and ecosystems, with pharmaceuticals like selective serotonin reuptake inhibitors (SSRIs) posing a significant threat to aquatic life. Fluoxetine, a common SSRI, contaminates waterways, affecting fish reproduction, behavior, and physiology, and potentially harming humans through the food chain. This study investigates the impact of fluoxetine, a common antidepressant, on the reproductive health and behaviour of zebrafish (Danio rerio). A cohort comprising 60 adult zebrafish, all approximately 3 to 4 months of age and exhibiting comparable developmental stages, was utilised for the investigation. These fish were randomly assigned to three distinct experimental groups: a control group, a low-dose group, and a high-dose group. Adult zebrafish were exposed to fluoxetine at concentrations of 0 (control), 40 ng/L (low dose), and 400 ng/L (high dose) for 28 days. Histopathological analysis revealed dose-dependent reproductive toxicity. In females, fluoxetine exposure caused detachment of the zona radiata in vitellogenin oocytes and increased the presence of atretic oocytes, indicating disrupted oogenesis. In males, exposure led to vacuolization in Sertoli cells and a potential reduction in spermatozoa, suggesting impaired spermatogenesis. Behavioural analysis using the novel tank test (NTT) showed that low-dose fluoxetine reduced anxiety-like behaviour, as evidenced by decreased latency to enter the top zone and increased time spent in the top zone. Conversely, high-dose exposure increased anxiety-like behaviour, with fish spending more time in the bottom zone. These findings demonstrate that fluoxetine, even at environmentally relevant concentrations, can negatively affect both the reproductive system and behaviour of zebrafish, highlighting the ecotoxicological risks associated with pharmaceutical contamination in aquatic environments.