Caffeine (CAF) has been considered an emerging environmental contaminant and its presence indicator of anthropogenic contamination. This study evaluated the effects of environmental concentrations of CAF (0, 0.5, 1.5, and 300 μg. L−1) on the behaviour of adult zebrafish (Danio rerio) after 7 days of exposure. The components of feeding, locomotion, boldness (new tank test), sociability (schooling test), and aggression (mirror test) were analysed. Growth rate and weight were investigated as complementary measures. CAF (0.5, 1.5, and 300 μg. L−1) reduced exploratory behaviour in zebrafish, increased feeding latency time (1.5, and 300 μg. L−1), and decreased growth rate and fish weight (300 μg. L−1). CAF also induced aggressive behaviour (0.5, 1.5, and 300 μg. L−1) and decreased appetence to the shoal (sociability) (0.5, and 1.5 μg. L−1). This study showed that low doses of CAF can induce behavioural effects in zebrafish that may have significant long-term impacts on vital ecological functions.