Abstract
Effects of water temperature and light intensity on aggressive behavior were examined in the juvenile yellowtails Seriola quinqueradiata (16-32mm TL). When fish were acclimated to water temperatures at 15, 20, 25, and 30°C, frequency of aggressive behavior increased with the increase in water temperature. Under the light conditions of total dark, 103, and 104 lx, the highest aggression was observed at 103 lx, whereas no aggression at dark. No aggressive behavior was observed at 10-3 lx whereas weak aggression occurred at 10-2 lx, suggesting the threshold of light intensity between 10-3 and 10-2 lx.
