Background. Atmospheric pressure is one of the most important factors affecting fish activity, but the potential influence on migration patterns of fish lacking a gas bladder is unclear. In this study, we analysed the influence of atmospheric pressure on round goby, Neogobius melanostomus (Pallas, 1814), from the coastal waters of the Black Sea. Material and methods. Gobies were maintained at low pressure, decreased by 1333 Pa (= 10 mmHg), for several hours a day at temperature intervals of 10-12°С, 14-16°С, 18-20°С, 22-24°С, and 26-28°С for 5 days and subsequently the pressure was returned to 1333 Pa and the results were compared to controls without pressure/ temperature changes. Results. We found that increasing the atmospheric pressure at temperatures 10-24°C influenced the activity of round goby, which then stabilised within one hour. Fish activity then decreased till it matches the level observed before experimental pressure changes. Changes in atmospheric pressure did not influence fish activity at higher temperatures of 26-28°C. Conclusions. We intended to determine the influence of atmospheric pressure and water temperature on the swimming activity of round goby. The association between the atmospheric pressure, thermal tolerance, and the fish activity levels is suggested as a possible mechanism driving migrations of the round goby.