Wakasagi

Wakasagi (Hypomesus nipponensis) are a small forage fish in the smelt family (Osmeridae) that are native to Japan and the Korean Peninsula. This species has one soft-rayed dorsal fin and has a maximum size of approximately 120 mm. The scales of Wakasagi are small and the fish appears almost translucent with a silvery-blue sheen. Wakasagi were intentionally introduced to California in 1959 from Japan by the California Department of Fish and Game as an experimental forage fish for trout and because of their similarity to Delta smelt (Hypomesus transpacificus). They were subsequently stocked in several reservoirs throughout the state. They are present in rivers in northern and central California, including the lower American River, the Sacramento River, the Mokelumne River, and other locations throughout the Sacramento-San Joaquin Delta.

Fun Fact: Wakasagi were once considered the same subspecies as the Delta smelt and they are known to occasionally hybridize.