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Rhodeus ocellatus

Rhodeus ocellatus
Rosy Bitterling
The Rosy bitterling (Rhodeus ocellatus) is a small fresh-water fish belonging to the family Cyprinidae (carp) and genus Rhodeus. Females are approximately 40-50mm long and males range from 50-80mm. Their bodies are flat with an argent-colored luster. However, males change to a reddish (sometimes purple) color during the spawning season (Mar~Sep) 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
Rosy bitterlings live in farm ponds (reservoirs) where freshwater mussels are abundant. Farm ponds are very important habitat for not only rosy bitterlings themselves also mussels and planktons. Freshwater mussels such as Dobugai play an important role in Rosy Bitterling reproduction.
Every female rosy bitterling has a unique pipe about the same length as its own body that is used for laying eggs on a (specific spot of mussels). Usually 2-3 eggs are laid at once and placed at the gill of the mussel. A male spawns into the gill cavity of the mussels right after a female lays eggs to ensure fertilization. Normally a female lays eggs repeatedly at 6-9 day intervals and about 10 times in a season.
Eggs grow in the mussel gill and juveniles stay inside of the mussel for approximately 15~30 days after fertilization. Eggs hatch after about 3 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. Usually juveniles grow around 40–50 mm within one year at which point they become adults. R. o. kurumeus(Nippon baratanago) live for approximately 3 years and rarely exceed this lifespan

Rhodeus ocellatus kurumeus which is used to be called R. o. smithi (Nippon baratanago) is a Japanese native species but Rhodeus ocellatus ocellatus (Tairiku baratanago) is found in China, Taiwan, as well as in Japan. Nippon baratanago was widely spread in the west side of Japan (Kyushu and western part of Honshū) before World War II. In 1942 Tairiku baratanago was accidentally introduced with grass (Ctenopharyngodon idellus) and silver carp (Hypophthalmichthys molitrix) from mainland China to Japan.
These two subspecies are morphologically very similar but there are several distinguishing characters such as the number of longitudinal scales, principal rays in the dorsal and anal fins, and shape of eggs. Also, R. o. ocellatus (Tairiku baratanago) has a silvery-white area anteriorly (white lines) on the ventral fin but R. o. kurumeus (Nippon baratanago) does not. In comparison the ventral fin of R. o. kurumeus (Nippon baratanago) is a dark color. Another notable difference is body size. R. o. kurumeus (Nippon baratanago) do not commonly exceed 60mm in length, whereas males of R. O. ocellatus are larger than 80mm and females of this subspecies commonly exceed 60mm (Tairiku baratanago)
Rhodeus ocellatus kurumeus (Nippon baratanago) was widely distributed in small ponds, reservoir, and creeks in Kyushu and the western part of Japan. However, since Rhodeus ocellatus ocellatus (Tairiku baratanago) was introduced, the population of Tairiku baratanago has been increasing dramatically all over Japan. By coexisting those two species in many area it tended to occur hybridization easily.
常见的鳑鲏属最大种,体高而侧扁,背鳍分枝软鳍条11-12根,臀鳍分枝软鳍条11-12根, 尾柄条纹蓝绿色带珠母光泽, 尾鳍中部具一红斑,鳞框明显而清晰,背部闪耀金色或金属绿色光泽,出水后腹侧反射蓝色光芒,,眼上部红色.模式亚种腹鳍前缘具白边.雄鱼臀鳍边缘有红色条纹,外镶细黑边或黑边不显,不同产地臀鳍的红色条纹宽窄不同,色泽浓淡也不同,发情期喉及腹部红色,体侧染紫红或粉红色