Transparent-scaled variant (TSV) of the rosy bitterling Rhodeus ocellatus ocellatus (Kner) was observed on both morphology and heredity. Compared with the normal-scaled type (NST), TSV is characterized by the blackish coloration in both eyes and peritoneum, and the luminescent one over the whole body. Histologically, the density of guanophores containing reflecting platelets was conspicuously low, especially in scale, iris, choroid and peritoneum, while the increase in the number of goblet cells (mucous cells) was recognized all over the dermal/epidermal regions. The heredity of TSV was recessive and supposed to be controlled by a single pair of genes unrelated to sex, judging from the result of crossbreeding experiments between NST and TSV. In growth and reproduction, no difference was seen between these two phenotypes. Transparent-scaled variant of the rosy bitterling can be competent for a genetic marker in experimental and developmental biology.