Epsilon Archive for Student Projects

Abstract

Pharmaceutical pollution is an emerging threat to aquatic ecosystems, yet its impact on complex social behaviours in fish remains underexplored. This thesis investigates how diazepam, a commonly detected Anxiolytic drug affects group spacing and social attraction in the shell-dwelling cichlid Neolamprologus multifasciatus. In a controlled laboratory setting, fish were exposed to three treatment levels of diazepam, control (0 μg/L), low (2 μg/L), and high (50 μg/L). Group spacing was assessed by analysing the spatial clustering of shell shelters used by the fish, while social attraction was evaluated through a two-choice behavioural task in a separate testing aquarium. Results showed that fish exposed to high doses of diazepam formed less clustered territories, indicating reduced group cohesion. In the two-choice sociality trials, high dose fish emerged more quickly from their shell shelters, spent more time near conspecifics, and exhibited increased exploratory behaviour. These changes suggest enhanced social attraction and boldness, consistent with diazepam’s known anxiolytic effects. The observed effects were dose-dependent, with stronger behavioural changes at higher concentrations. The effect on social attraction were stronger in females, who showed stronger behavioural changes than males. These findings demonstrate that diazepam can alter both spatial and social behavioral aspects of a group living social fish species. Such behavioural disruptions show the need to consider complex social behaviours when evaluating the environmental impact of pharmaceutical contaminants.