Results from previous studies suggest that both types of eels are basically nocturnal predators [33, 34, 36]. Our results confirmed that eels in this area also forage mainly at night: the amount of stomach contents in both types of eels captured before noon was greater than that in eels captured after noon. Although this tendency might be more pro- nounced in C. myriaster because these had empty stomachs after noon, the foraging times of the two species appear to overlap in Kojima Bay.