Critical swimming speed of the southern straight-mouth nase Pseudochondrostoma willkommii (Steindachner, 1866), a potamodromous cyprinid from southern Europe

Critical swimming speed (U_crit) of the potamodromous southern straight-mouth nase was assessed in a modified Blazka-type swim tunnel. Forty-one P. willkommii were tested and exhibited a mean± SD U_crit of 0.54 ± 0.07 m/s. The sex of experimental fish had no effect on U_crit but a significant positive relationship was found between swimming performance and the body condition of tested fish. Results from this study can be used to improve the current design of fish passes targeting this, or similar, potamodromous fish species.