Fig. 5

Heart rate detection in conscious, unrestrained, group-housed zebrafish. a Single frame from color-magnified video of wild-type conscious and unrestrained adult zebrafish (Additional file 7). b Magnification of box in a with a display of regions of interest (yellow rings) tracking the ventral surface of the thoracic region as the fish moves gently. c Vertical scan line from magnified video over time showing temporal variation of color at the level of the thoracic region. d Thoracic and background signal (yellow and gray rings in b) development over time (blue channel). e Fourier-transformed blue channel signal in d in the frequency domain. f Displacement in percent of fish total length (TL) (left vertical axis) and speed in TL/s (right vertical axis) of thoracic region of interest (yellow rings in b) during the recording. Although the fish movements are rapid and occur at a high rate, the displacement is small and the rate is out of the frequency range of the beating heart (compare d with f). g Fourier-transformed speed of displacement signal in f in the frequency domain. Scale bars in a and b are approximations (indicated by dotted lines) based on average zebrafish sizes in the batch since the fish was at an unknown depth in the water column during the recording