First record of some aquarium medaka varieties such as “Taigaiko-medaka”, in the field in Gifu Prefecture, Japan

Abstract

The medaka fish (Oryzias latipes species complex) were collected in Mino City, Gifu Prefecture, Japan, on November 2021. A total 74 individuals were collected and observed for morphological characteristics, of which 24 individuals had a metallic luster on their dorsal surface. These morphological characteristics are consistent with those of the “Taigaiko-medaka”, and therefore they are aquarium medaka varieties. Other aquarium medaka varieties such as blue-colored medaka and those with many silvery scales were also collected. These were presumed to have been abandoned in the field by aquarium owners because they were not needed after breeding selection.