Effect of tail fin loss on swimming capability and tail beat frequency of juvenile black carp Mylopharyngodon piceus

Fin clipping is a common practice in fisheries management, and hatchery fish are often marked this way. In the wild, the tail (caudal) fin may be damaged or lost to predation or disease. Because the tail fin is important to fish swimming behavior and ability, this study was designed to examine the effects of partial and complete loss of the tail fin on the swimming ability of juvenile black carp Mylopharyngodon piceus. Swimming speed and tail beat frequency were measured for 3 groups (intact tail fin, partial tail fin, no tail fin) using a stepped velocity test conducted in a fish respirometer. We found that critical swimming speed (U-crit) and burst speed (U-burst) decreased slightly in the partial fin group and significantly in the no fin group. In the group with no tail fin, U-burst decreased more than U-crit, clearly reducing the ability to avoid predators. Moreover, mean tail beat frequency (TBFmean), U-crit and U-burst all decreased slightly in the partial fin group and significantly in the no fin group. A decrease in tail beat force and TBF both reduce swimming capability. These findings contribute to developing our understanding of the relationship between fish tail fins and swimming.