Abstract
The effects of light-dark (LD) and meal-fast (MF) cycles on demand-feeding and locomotor activity rhythms were examined in individual rainbow trout. Demand-feeding and locomotor activity rhythms were synchronized to both LD and MF cycles. Demand-feeding was shown mainly during L phase in LD 12:12 and M phase in MF 12:12. The locomotor activity pattern recorded at the upper and lower layer of the tank tended to be in- and anti-phase of demand-feeding pattern, respectively. Both demand-feeding and locomotor activity rhythms free-ran under constant conditions after both LD and MF cycles, indicating that MF cycle can act as a Zeitgeber as well as LD cycle. Free-running periods of demand-feeding and locomotor activity rhythms tended to be inconsistent within individual. The findings in the present study suggest the possible involvement of multiple oscillators.
