Fish behaviour was monitored with a Sony XC-77 CCD video camera module equipped with a Nikon 55 mm lens,positioned directly over the recording chamber. Video recording was made with a Sony Digital NR/TBC Hi8 Pro video cassette recorder (VCR) (Fig. 1). A Sony VCR Plus EV-S7000 was used to write a time-code onto each individual video frame of the selected video segments.
Alternatively, it is possible to use an Hi8 Videorecorder that permits simultaneous time-code writing during the recording session.Two table lamps were placed to the side of the recording
chamber and adjusted prior to each recording session to ensure adequate illumination of the chamber and prevent light reflections from the water surface.