As global demand for medications continues to increase, pharmaceutical pollutants are being introduced into the environment at an alarming rate. A particularly pervasive pharmaceutical pollutant is the antidepressant venlafaxine, which has become one of the most widely detected pharmaceuticals in the environment today. The receptors targeted by venlafaxine are conserved across most animal groups, and venlafaxine can therefore disrupt ecologically important traits in non-target organisms. Nevertheless, research into the impacts of venlafaxine in the environment, particularly at environmentally relevant concentrations, remains limited. As such, our study aimed to investigate whether exposure to environmentally realistic concentrations of venlafaxine affected a suite of ecologically important behaviours in eastern mosquitofish (Gambusia holbrooki). Using a static renewal system, fish were subjected to either an unexposed freshwater control (i.e. no venlafaxine), low-venlafaxine exposure (0.5 µg/L), or high-venlafaxine exposure (1 µg/L) for 28 days. These concentrations were selected to reflect realistic levels of venlafaxine observed in the natural environment. Following the 28-day exposure period, individuals completed behavioural trials to test activity and exploration in a novel environment, boldness, and foraging behaviour. We will discuss the results of our findings in the broader context of a small but growing body of literature focused on highlighting the effects of psychoactive pharmaceuticals on anxiety-related behaviours in wildlife.