Iwana Sushi

In Japanese, iwana stands for the genus of char (lat. Salvelinus), which belong to the salmonid family. In Japanese cuisine, the term iwana refers predominantly to the whitespotted char. Both marine and landlocked freshwater forms of iwana exist.

The bright and shiny, white to reddish meat has a light and pleasing taste. The smell is very neutral and the aromas are subtle. The taste of the meat can be intensified by marinating in vinegar marinade (sujime). Iwana is therefore also suitable for preparation as „pressed sushi“ (oshi-zushi, 押し寿司).

Compared to salmon, which belongs to the same family, the taste of iwana is less full-bodied and more restrained. In particular, char that spend most of their lives in fresh water have a slightly “earthy” flavor. The condition of the water from which the fish were taken is responsible for these off-flavors. Microorganisms in the water produce geosmin, especially Streptomyces species and cyanobacteria, myxobacteria. These organisms live mainly in the ground of the water. Geosmin formation by cyanobacteria can provide an earthy odor in freshwater and is difficult to remove from because the perception threshold is very low. [Petersen et al., 2014]

The spawning season depends on the region and subspecies. It takes place in many tributaries of the main stream from October to January. In spring and summer, when the water temperature is high, the fish is fatty and tasty, but after October, when it enters the spawning season, the meat tastes a little less tasty [Yamagata, 2015].

Iwana offered on the market often come from aquaculture and are available all year round.

The tratidional character for iwana 𩸶 or 岩魚 is composed of the character for “rock“ 岩 (iwa, いわ) and “fish“ 魚 (sakana, さかな). This can be interpreted as a fish that lives in mountain streams or prefers a rocky environment.

Iwana prefers fast flowing, oxygen-rich, cool and clear waters with gravel or sand bottom. They are fast swimming predators that feed on small organisms, water insects, other fish, insects falling from shore trees and frogs.

Some iwana groups live anadromously, that means they migrate from saltwater to freshwater for spawning, these are called amemasu (アメマス) in Japanese. The term ezoiwana (エゾイワナ) is used to describe groups of iwana living in landlocked freshwater areas. Ezoiwana prefers rivers and streams with a water temperature below 15°C.

The distribution in rivers extends over different regions of Honshu and Hokkaido. In addition, the natural habitat includes the northeastern Korean peninsula via Sakhalin, the Kuril Islands to Kamchatka in the Northwest Pacific.

The characteristics of iwana vary greatly from one region to another, but it is common to classify the whitespotted char into four subspecies: Ezo-iwana, nikkou-iwana, yamato-iwana and gogi. Furthermore, a distinction can be made between the whitespotted char and the dolly varden trout.

1. PARASITES: The meat, especially that of wild-caught specimens, may be infested with parasites that cause infectious diseases. Infection can be avoided if the raw meat has been adequately frozen. Pickling and soaking in salt or vinegar solution is not sufficient to eliminate the parasites. If the product has been farmed, only raw unprocessed seafood from production facilities whose products are approved for raw consumption should be consumed. [Sakurada, 1984]