Induced flow speed and its relationship to body length of two Schizothoracinae fishes in upper reaches of Yellow River

To investigate the response of fish induced flow speed to body length, we tested the induced flow speed of two Schizothoracinae fishes with different body lengths by increasing velocity in mobile Brett-type swim tunnels. Results show that the absolute induced flow speed of Gymnocypris eckloni Body length (BL): (20.67±3.65) cm and Schizopygopsis pylzovi BL: (14.50±2.24) cm were (4.97±1.22) cm·s⁻¹ and (4.52±0.9) cm·s⁻¹, respectively; and their relative induced flow speed were (0.24±0.045) BL·s⁻¹ and (0.31±0.052) BL·s⁻¹, respectively. The absolute induced flow speed was positively related to fish body length, while the relative induced flow speed was negatively related to fish body length since the increasing rate of the absolute induced flow speed was less than that of body length. There was no significant difference in the absolute induced flow speed between these two Schizothoracinate fishes (P>0.05). The constructed non-linear regression model can explain the response of fish induced flow speed to body length effectively. This study provides some guidance for the qualitative prediction of fish swimming characteristics in other areas where it is difficult to capture test samples, and also provide basic data for the design of fish facilities.