The Effects Of Caudal Fin Loss And Regeneration On Fast-start Performance In Juveniles Of Two Cyprinid Fish Species

To investigate the effects of caudal fin loss and regeneration on fast-start performance of crucian carp(Carassius auratus, inhabiting in open habitats) and pale chub(Zacco platypus, inhabiting in rip current),16juveniles of both crucian carp (body length,6.27±0.04cm) and pale chub (body length,6.14±0.12cm) were allocated to two groups, respectively. One group (8fish) for the treatment of caudal-fin-amputation-regeneration (20days) and re-amputation, the other group (8fish) for control. The movement of each fish was recorded by a high-speed camera after an electric stimulation for the analysis of fast-start parameter. Furthermore, the morphological parameters such as body length (L), body length (H), fitness ratio (FR), caudal fin aspect ratio (AR), relative caudal fin area ratio and caudal fin index (FI) in the two cyprinid fish species were measured. The experimental water temperature was maintained at (25.0±0.5)℃.The results are as follows:1. The crucian carp showed a significant lower FR and higher FI than pale chub (p<0.01), but the maximum linear velocity (Vmax), escape distance (d), relative turning radius (TRr) and bending coefficient (BC) showed no significant difference between the two cyprinid fish species.2. The Vmax, d and TRr during fast-start process of both fish species decreased significantly after caudal fin loss (p<0.01), with the Vmax of crucian carp decreased by39%while that of pale chub decreased by24%after caudal fin loss.3. After20days’recovery, the areas of caudal fin of both fish species recovered about60%those of the caudal-fin-intact fish. However, the Vmax, d, RTr and BC of both caudal-fin-regenerated crucian carp and pale chub showed no significant difference compared with those of the control groups, respectively. Compared to the control group, the decrease of Vmax of crucian carp and pale chub after the second amputation (17%and9%) was smaller than the first amputation (39%and24%). The decrease ratio between the first and the second caudal fin amputation in crucian carp was larger than that of pale chub. However, the bending coefficient (BC) of pale chub increased significantly after the second caudal fin amputation compared with those of fin-intact group (p=0.046). In conclusion:1. The habitat showed a more profound effect on the body shape of both fish species than fast-start performance2. Tthe caudal fin of crucian carp played a more important role than that of pale chub during fast-start movement3. The pale chub which prefer to rip current habitat showed more significant functional compensation after20days’recovery.