Diel activity and reproductive territory of the Japanese bagrid catfish, <Emphasis Type="Italic">Pseudobagrus ichikawai</Emphasis>

The endangered Japanese bagrid catfish, Pseudobagrus ichikawai, is typically nocturnal, emerging from shelters, such as crevices along the shore, at sunset to actively forage in open areas throughout the night with short-term movements of up to 40 m (except for mature males). Just before sunrise, individuals return to their shelters, from which they rarely emerge in daytime. Mature males (3 years-of-age or older) are found only in the vicinity of their shelters of during both day and night, which they defend with strong territorial behaviour. The restricted reproductive resources (shelters) probably severely limit the population size and reproduction in this species.