Effect of Temperature on Spontaneous Locomotor Activity of the Saddler Bichir Polypterus endlicherii (Polypteridae)

Using the open field method, the spontaneous locomotor activity of the saddler bichir Polypterus endlicherii has been estimated at different water temperatures (20, 25, 30, and 34°C). The locomotor activity of the fish increases by 1.40 times in the temperature range of 20–25°C (temperature coefficient 2.1); more strongly (2.00 times) it increases in the temperature range of 25–30°C (4.1), while in the range of 30–34°C (1.1) it changes insignificantly (1.04 times). With an increase in temperature, the swimming speed and the distance covered by the fish in one hour increase; subsequently, the time spent on crossing the test line decreases. The coefficient of variation of the locomotor activity index decreases with an increase in temperature. Comparison with the previously studied Senegal bichir P. senegalus revealed both similarities and differences in the locomotor activity of these two sympatric species.