Unagi is a highly prized ingredient in Japanese cuisine, recognized globally as a delicacy for its rich flavor and unique texture. The term refers to freshwater eel, which is generally served grilled and glazed, offering a distinctive sweet and savory experience.
Defining Unagi
Unagi primarily refers to the Japanese eel, scientifically classified as Anguilla japonica, a species native to East Asia. This eel is a catadromous fish, meaning it spawns in the ocean but spends the majority of its life developing and growing in freshwater rivers, estuaries, and brackish waters. The eels undertake a long migration from their spawning grounds near the Mariana Islands to the rivers of countries like Japan, China, and Korea.
The adult eel has a long, serpentine body with dark, often greenish-black skin and a yellowish-white abdomen. Its distinct flavor profile is a result of its high-fat content, which is significantly richer than that of its saltwater counterpart, anago. When cooked, the flesh has a buttery texture and is firm and tender, carrying a deep umami flavor with sweet, earthy undertones.
Traditional Preparation and Serving
The preparation of unagi centers on a technique known as Kabayaki, which involves filleting, deboning, and skewering the eel before grilling. In the Kanto (Tokyo) style, the eel is first grilled, then steamed to remove excess fat and tenderize the meat, and finally grilled again. The Kansai (Osaka) style skips the steaming step, resulting in a crispier skin and a more intense texture.
Throughout the grilling process, the eel is repeatedly basted with a thick, syrupy glaze called tare. This sauce is crafted by reducing a mixture of soy sauce, mirin (sweet rice wine), sake, and sugar to achieve a glossy, caramelized consistency. The repeated basting allows the tare to penetrate the meat while creating a slightly charred, savory crust that balances the eel’s natural richness.
Unagi prepared in the Kabayaki style is most famously served as Unadon or Unaju, both featuring the glazed eel over a bed of steamed white rice. Unadon presents the eel in a simple, deep ceramic bowl (donburi). Unaju is considered a more formal presentation, served in an elegant, rectangular lacquered box (jubako). A powdered spice blend called sansho, which has a slight citrusy, peppery bite, is traditionally sprinkled over the dish to cut through the richness of the fatty eel and the sweet glaze.
Sourcing, Conservation, and Sustainability
The vast majority of unagi consumed today comes from aquaculture, or eel farming, which developed in Japan starting in the late 19th century. However, this farming process is not a closed-cycle operation because the Japanese eel has never been successfully bred in captivity for commercial purposes. Consequently, eel farms rely on catching wild glass eels, or elvers, the transparent juvenile stage that migrates from the ocean into coastal rivers.
This reliance on wild-caught juveniles means that the aquaculture industry directly contributes to the depletion of the wild population. The species Anguilla japonica has faced a dramatic decline in stock numbers over recent decades due to a combination of overfishing of the elvers, habitat loss, and changing ocean conditions affecting spawning success. Because of these factors, the International Union for Conservation of Nature (IUCN) currently lists the Japanese eel as an endangered species.
Efforts to promote sustainability include international agreements to manage the catch of glass eels and ongoing research into developing a fully closed-cycle aquaculture system. Until a breakthrough in captive breeding is achieved, the consumption of unagi remains linked to the health and recovery of the endangered wild population.