Post-release change of home ranges and diel movement patterns of hatchery-reared black-spot tuskfish Choerodon schoenleinii were examined using ultrasonic telemetry. Nine hatchery-reared C. schoenleinii were released in Urasoko Bay, Ishigaki Island, Okinawa, Japan and monitored using ultrasonic telemetry. The fish gradually increased home ranges for c. 3 months before establishing stable home ranges. This pattern of home-range change might have been associated with the learning process of natural environments and intraspecific and interspecific competition. The fish also showed strong diurnal movement patterns: moving horizontally and vertically during the day and staying in the same place at night. The behaviour observed in this study is highly valuable to determine when, where and how to release the fish as well as how to increase the fitness of the fish before releasing.