The intraspecific relationships within the juvenlle and young bastard halibut have been studied in a growing area in the Genkai-Nada at approximately monthly intervals during 1976 and 1977, based on the stomach contents examined.
At a depth of 5m, many halibut under 120mm in total length were found in May to October, feeding mainly on Mysidacea.
At a depth of 5m in 1976, change of the abundance of the halibut, change of the abundance of Mysidacea in the benthos fauna, and change of the amount of Mysadacea in the stomach of the halibut generally showed similar trands. In July to September, the amount of Mysidacea in the stomach decreased extremely accompanied by the following phenomena: (i) fall of the index of stomach fullness, (ii) difference of the stomach contents between small-sized fish and large-sized ones.