2023 Volume 17 Pages 47-55
In 2022, the introduced species Macropodus ocellatus was collected from the Kiso River system in Gifu Prefecture. Although M. ocellatus has been found in the Kiso River system, there was no description of where it was collected and no referral record identifying it as being in Gifu Prefecture. Therefore, this is the first record of M. ocellatus in Gifu Prefecture and the first record in the Kiso River system in about 60 years. Although the details of the origin of this species in Gifu Prefecture are not known, it has been distributed as a rare fish in Japan and its population has been decreasing. Therefore, it is possible that M. ocellatus was intentionally released by individuals or ornamental fish traders to introduce it to the Kiso River. There is concern that M. ocellatus may spread in the Kiso River system, and therefore, it is necessary to monitor its distribution, expansion and habitat status, and to exterminate it.
