The minimal dark adaptation time and the minimal time interval of light stimulation were determined in dark-adapted zebrafish Daniorerio with body length of 3.5-4.0 cm exposed to various dark adaptation periods,flash stimulation time interval (10,20,30,40,50,60,70,80,90 s and 100 s)and wavelength stimulus light (340-620 nm)in an electroretinogram (ERG)experiment and the spectral sensitivity of dark-adapted zebrafish was analyzed by using the b-wave amplitude component of the ERGs as the response to light stimulation to investigate the spectral sensitivity and the optimal parameters in the ERG test.The results showed that the zebrafish had dark adaptation time of at least 90 min(student’s t test,P>0.05),and the light stimulation time interval of at least 50 s(paired t test,P>0.05)in the ERG test.The sensitive peaks in spectral sensitivity function of dark-adapted zebrafish were detected in both visible spectrum (at 500 nm)and UV spectrum (at 365 nm),with about 0.28 lg units lower in the peak value in UV sensitivity than that in visible spectrum.The findings indicated that dark-adapted zebrafish were found to be sensitive to both visible and ultraviolet light,and the U-cones and rods in their retina participated in dark vision,which led to increase the sensitive spectrum range and to improve the sensitivity of dark vision.
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