Relationships between ΔTS (Eq. (1)) at the frequency of 70 kHz and vertical swim velocity, VSV, for studied fishes: Sg1, Sg2, Mc, Tz, Oa, Cc1, and Cc2 (see Tab. 1 for species abbreviation). Large empty dots and vertical bars represent the means and 25th–75th percentile ranges of the ΔTS at each 0.02 m s⁻¹ VSV bin. The means and 25th–75th percentile ranges are calculated for bins with >14 data points. The changes of ΔTS with VSV reveal different species-characteristic patterns.