Temperature Preference and Locomotor Activity in a Thermogradient Field of the European Bitterling Rhodeus amarus (Acheilognathidae)

The results of experimental studies on thermopreferential behavior and motor activity of the European bitterling Rhodeus amarus under thermogradient field conditions are presented. The thermopreferential range of the European bitterling was 17–29°C, within which, the temperature interval of 21–25°C was the most frequented by fish and appeared to be optimal for the life activity of the species. The mean preferred temperature was 22.4°C. Temperatures below 17 and above 29°C were avoided by the bitterlings when swimming in the thermogradient. The fish showed high locomotor activity, swimming an average of 84.7 m per hour with an average speed of 2.3 cm/s. While moving in the thermogradient, the fish experienced temperature variations averaging 0.12°C/s. The data obtained on the thermal biology of the European bitterling can expand the understanding of the invasive potential of the species.