Effect of time-restricted feeding on 24-h rhythm in phototactic behavior of zebrafish

Abstract

ABSTRACT Among all other repertoire of behaviors, phototactic behavior is one of the most vital behaviors. Our knowledge on the impact of time-restricted feeding on phototactic behavior of fish is critically limited. In this study, we examined the effect of time-restricted feeding schedule on 24-h rhythm in phototactic behavior of zebrafish (Danio rerio). We kept fish in the specially designed aquaria consisting of a photic and a non-photic zone under natural day length condition and fed once in a day, either randomly or at 1200 or 1600. We recorded the frequency of fish in the photic zone every day between 1000 and 1800 for six to nine consecutive days. Statistically significant 24-h rhythms in the frequency of fish were validated at the group level, irrespective of the feeding schedule. It is difficult to explain why the fish fed at 1200 only exhibited food anticipatory activity (FAA). The 24-h average decreased and acrophase delayed significantly in this group as compared with the others. The amplitude of the phototactic rhythm dampened under restricted feeding condition as compared with the fish on random feeding. Nonetheless, the present findings underscore the role of time-restricted feeding as a powerful modulator of the 24-h rhythm in phototactic behavior.