Fig. 4. (A–C) Velocity and vorticity values for one trial with Lepomis (A), one trial with Colomesus (B) and one with Thysochromis (C) as function of time (60 s). Maximum velocity in the field of view (top), mean velocity in the field of view (middle) and maximum vorticity in the field of view (bottom) are shown. Different colours refer to different layers (black, layer 1 = uppermost layer; red, layer 2; green, layer 3; blue, layer 4; cyan, layer 5; magenta, layer 6 = lowermost layer.