Wikipedia
Ariakehimeshirauo
The ariakehimeshirauo, Neosalanx reganius, is a species of icefish in the Salangidae family endemic to Japan. It is only known from Midori and Chikugo Rivers in Kyushu. Its maximum total length is , and has a lifespan of about one year. It seems to be relatively rare in its limited habitat, and is classified as a vulnerable species by IUCN.
N. reganius is an estuarine species, usually found in turbid waters with low salinity, or in fresh water. It is a planktivore. Relative to its size, it is highly fecund (347–1071 eggs per female), and the ovaries of gravid females made up 44% of their total body weight, on average.