The circadian activity system may contain two independent oscillators: a food-entrainable oscillator (FEO) and a light-entrainable oscillator (LEO). Many animals manifest food-anticipatory activities when subjected to daily schedules with periods of restricted food availability. However, no studies have examined whether these two oscillators regulate feeding activity (FA) and locomotor activity (LA), respectively. To know the regulation of these behaviours, simultaneous recordings of FA and LA were obtained from Japanese sea catfish, Plotosus japonicus in the absence or presence of food, under RF conditions with light/dark (LD) cycles and under light/light (LL). In the absence of food, the catfish showed nocturnal LA, but no FA. Under ad libitum food conditions, both activities occurred during the dark period and were synchronized with LD cycles. FA lasted for 11-24 days when food was stopped after ad libitum food availability. RF during the light phase produced both food-anticipatory and light-entrainable feeding activity. Furthermore, this condition produced weak food-anticipatory and light-entrainable locomotor activity. Under the LL condition, RF produced food-anticipatory feeding and locomotor activities, suggesting that a food-entrainable oscillator controls both the activities. However, under the LL condition, light-entrainable feeding and locomotor activities were not observed, suggesting that a light-entrainable oscillator controls FA and LA. During RF schedule, LD cycle shifts resulted in disrupted synchronization of FA onset in three of the four fish, but one fish showed synchronized FA. These results suggest that the FEO and LEO may control feeding and locomotor activities, respectively, and that FEO may control food-anticipatory activities.