The distribution of Nipponocypris temminckii was investigated in 24 rivers in Nagano, Niigata, Yamagata, Akita, Iwate, and Aomori Prefectures, the species being collected at seven study sites. Amongst non-benthic fishes, N. temminckii was exclusively dominant in two rivers. Supplementary records of the species in Nagano, Niigata, Akita and Iwate Prefectures were also described. Rivers in which investigations had been conducted over two or three years showed an increasing proportion of N. temminckii, indicating successful colonization of the species.
