Development of a vision-based automatic vaccine injection system for flatfish

► We developed a vision-based automatic vaccine injection system for flatfish. ► We validated the performance of the proposed algorithm by analyzing the injection error. ► The proposed algorithm allowed an injection rate of 2000 per hour on average. ► Vaccination of flatfish with a body length of up to 500 mm was possible, even when the orientation of the fish was random. ► Injection errors in sizes of flatfish were ranged as 0-0.6 mm indicating very low in error.