Predator-inducible defences constitute a widespread form of adaptive phenotypic plasticity, and such defences have recently been suggested linked with the neuroendocrine system. The neuroendocrine system is a target of endocrine disruptors, such as psychoactive pharmaceuticals, which are common aquatic contaminants. We hypothesized that exposure to an antidepressant pollutant, fluoxetine, influences the physiological stress response in our model species, crucian carp, affecting its behavioural and morphological responses to predation threat. We examined short- and long-term effects of fluoxetine and predator exposure on behaviour and morphology in crucian carp. 17 days of exposure to a high dose of fluoxetine (100 µg L^-1), resulted in a shyer phenotype, regardless of the presence/absence of a pike predator, but this effect disappeared after long-term exposure. Fluoxetine effects on morphological plasticity was context dependent as a low dose (1 µg L^-1) only influenced crucian carp body shape in pike presence. A high dose of fluoxetine strongly influenced body shape regardless of predator treatment. Our results highlight that environmental pollution by pharmaceuticals could disrupt physiological regulation of ecologically important inducible defences.