Fig. 1. Behavioral red cone sensitivity at different times in the day and night in zebrafish that were kept in LD and 2 days in DD. In both LD and DD, red cone sensitivity increased during the day and decreased at night. Horizontal bars at the top of the figure indicate lighting conditions; white bar, day; black bars, night; gray bars, subjective days without light. Data represent the mean ± S.E.M. (N=8).