Effects of the Light-Dark Cycle and Scheduled Feeding on Behavior and Reproductive Rhythms of the Cyprinodont Fish, Medaka, Oryzias latipes

Medaka were maintained on a 16∶8 light-dark cycle and fed once daily on one of 5 different feeding schedules. The daily rhythm of agonistic behavior rapidly entrained to the scheduled feeding time and maintained this entrainment during a 3-day starvation period. In contrast the daily rhythms of egg laying and courtship stayed entrained to the L:D cycle regardless of the feeding schedule. Thus, temporal integration of this fish with its daily environment can involve multistimuli which concurrently and differentially entrain externally expressed circadian systems