Some 200,000 young sweetfish swim at the Kanagawa Prefectural Fisheries Technology Center's freshwater fisheries experiment station in the city of Sagamihara, south of Tokyo, in this recent photo. The shining sweetfish, called "shirasu ayu" in Japanese, hatched last autumn and are now some 4 centimeters in length. Once the young fish are big enough, fishery industry workers release them into local rivers, such as the Tama River that runs through Yamanashi, neighboring Tokyo and Kanagawa prefectures and the Sagami River in Kanagawa. The population of sweetfish significantly varies from year to year, so such breeding facilities are necessary to keep the ecosystem balanced.
(Japanese original by Tatsuro Tamaki, Photo Group)