Nocturnal activity and feeding of juvenile channel catfish, Ictalurus punctatus, around offshore breakwaters in Lake Kasumigaura, Japan

Diel changes in occurrence and feeding habits of juvenile channel catfish (Ictalurus punctatus) were examined in offshore breakwater areas in Lake Kasumigaura, Japan, to understand their nocturnal behavioral ecology within a lentic habitat. Juveniles (20-56mm in standard length) occurred more abundantly in evening and nighttime than in daytime and fed mainly during darkness hours. Major food items comprised chironomid larvae and cladocerans. The relative proportion of those items in stomach contents changed from daytime to evening and nighttime, possibly being partly related to diel changes in prey accessibility.