Effect of temperature on swimming performance in juvenile southern catfish (Silurus meridionalis).

The critical swimming speed (U(crit), aerobic swimming performance) and endurance (anaerobic swimming performance) of juvenile southern catfish Silurus meridionalis Chen (9.8+/-0.1 cm body length and 8.09+/-0.17 g body mass, n=226) were investigated at 10, 15, 20, 25, and 30 degrees C. Both absolute U(crit) (cm s(-1)) and relative critical swimming speed (U(r), BL s(-1)) of juvenile southern catfish increased in the temperature zone from 10 to 25 degrees C (p<0.05) and plateaued between 25 and 30 degrees C. However, the relationship between endurance time (tested at 1.23, 1.59 and 1.79 U(r-max)) and temperature followed an approximate bell-shape curve as temperature rose (p<0.05). The optimum temperatures of maximal U(crit) (3.40 BL s(-1)) of juvenile southern catfish was 28.4 degrees C. But that of experimental fish's endurance which was tested at velocity of 1.59 and 1.79 U(r-max) was 23.2 degrees C. These results show that temperature has a significant effect on swimming performance in juvenile southern catfish.