Freshwater ecosystems contain 41% of the world's known fish species (Daily, 1997). Unfortunately, freshwater biodiversity faces many threats. Aquatic environments, and especially small bodies of the water, are currently one of the most degraded types of ecosystems (WWF Living Planet Report, 2020). Pharmaceuticals are a threat to modern biodiversity. The reason is permanent presence of pharmaceutical substances in the freshwater ecosystems (Hughes et al., 2013). Among these medicines, there is the commonly used and increasingly prescribed antidepressant, fluoxetine (Prozac), a selective serotonin reuptake inhibitor (Schultz et al., 2010;Silva et al., 2012). The medicine is prescribed in the case of depression, anorexia, bulimia, obsessive and compulsive disorder, panic disorder etc., and became the third most frequently consumed group of pharmaceuticals (Mojtabai & Olfson, 2011). Two main sources