Fig. 7. Simultaneous dorsal and anal fin jet development in brook trout manoeuvring at 0.5 L s^-1. The fish is manoeuvring away from the stimulus located beyond the top of each image. (A) Dorsal fin at peak amplitude. (B) Dorsal fin peak jet velocity. The peak jet formation by the dorsal fin occurs just after maximum kinematic excursion with less phase lag than that seen in steady swimming. (C) Anal fin at peak amplitude and jet velocity. There is no phase lag between peak amplitude and peak jet velocity. Note that the pelvic fins appear as paired bright circular regions in the dorsal view because they intersect the ventral light sheet and reflect light into the dorsal camera. Similar pelvic fin reflections can be seen in the dorsal views shown in Fig. 6. Note that x and y axes represent the scale of the video image.