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The rosy bitterling (''Rhodeus ocellatus'') is a small freshwater fish belonging to the family Cyprinidae (carp). Females are about 40-50 mm long and males are 50-80 mm. Their bodies are flat with an argent-colored luster. However, males change to a reddish (sometimes purple) color during the spawning season (March to September) which functions to attract females. This reddish color is similar to the color of a red rose, which is why it is called a rosy bitterling.〔加納義彦. ニッポンバラタナゴの保護と環境保全. 第５回日本水大賞受賞活動集. 日本水大賞顕彰制度委員会. 42－45. 2003.〕 ==Ecology and reproductive system== Rosy bitterlings live in ponds (reservoirs) where freshwater mussels are abundant. Farm ponds are an important habitat for not only rosy bitterlings, but also mussels and plankton. Freshwater mussels play an important role in rosy bitterling reproduction. The female rosy bitterling has a unique pipe about the same length as its own body, used for laying eggs on a specific spot of mussels. Usually, two or three eggs are laid at once and placed on the gill of the mussel. A male spawns into the gill cavity of the mussels right after a female lays eggs to ensure fertilization.〔Kanoh, Y. 2000. Reproductive success associated with territoriality, sneaking, and grouping in male Rosy Bitterlings, ''Rhodeus ocellatus'' (Pisces: Cyprinidae). Env. Biol. Fish. 57: 143-154〕 Normally, a female lays eggs repeatedly at 6- to 9-day intervals about 10 times in a season. Eggs grow in the mussels' gills and juveniles stay inside the mussel about 15 to 30 days after fertilization. Eggs hatch after about three days when juveniles are about 2.8 mm long. The body has a unique shape resembling the bud of a matsutake mushroom. Juveniles swim out of the mussel from the margin of the excurrent siphon. At this point, juveniles are about 7.5 mm long and about the same shape as adults.〔Nagata, Y. 1976. Reproductive behavior of a bitterling, Rhodeus ocellatus (Kner). Physiol. Ecol. Japan 17: 85-90 (in Japanese)〕 Usually, juveniles grow around 40–50 mm within one year, when they become adults. ''R. o. kurumeus'' (Nippon baratanago) lives about three years and rarely exceeds this lifespan.〔Kimura, S., and Nagata, Y. 1992. Scientific name of Nipponbaratanago, Japanese bitterling of the genus Rhodeus. Japan.J.Ichthyol. 38: 425-429〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Rosy bitterling」の詳細全文を読む スポンサード リンク
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