[1][2]Ryukin goldfish, Plate XIX in: Goldfish and Their Culture in Japan, by Shinnosuke Matsubara*Yamagata kingyo (yamagata goldfish) or sabao (mackerel tail) or tamasaba - a hardy single-tailed variety of the ryukin that has been developed in the Yamagata Prefecture of Northern Japan. * Tetsu onaga (iron-colored longtail) - a rare iron-colored variety of the ryukin.