Aquaculture: Japanese Eel

How hungry would you have to be to eat an eel? In Japan, they don’t have to be very hungry at all; Japan is the number one consumer of Anguilla japonica, the Japanese Eel.

Production of Japanese Eel through aquaculture (farmed) and wild capture, data from FAO,

The Japanese Eel has a long, cylindrical body, capable of growing to nearly 5 feet and weighing just over 2 pounds. The lower jaw of the Japanese Eel protrudes slightly, with small cone-shaped teeth. They have contiguous fins along the upper and lower sides of the body to the tip of the tail. The Japanese Eel can be found from the Pacific coast of Japan to the Philippines.

Unajyu, prepared by chefs at the Michelin-starred restaurant Hashimoto in Tokyo, consists of eel served over rice and is commonly served during the summer for the Day of the Ox. Photo by AP Photo/Sherry Zheng,

Japanese Eels are catadromous, which means, like the salmon, they spend part of their lives in freshwater and part of their lives in the ocean. While salmon return to rivers to spawn, the Japanese eel does the opposite, spending their lives in rivers and mountain lakes and returning to the ocean to spawn, usually near seamounts. The catadromous behavior of the Japanese Eel is variable; some eels only travel into estuaries, while others spend their entire lives at sea.

Top producers of farmed Japanese Eel, from FAO,

Aquaculture of Japanese eels began in Tokyo in 1879, before spreading to China, the Republic of Korea, and Malaysia and was a response to declining wild stocks of eels. Young eels, called glass eels or elvers, are collected from the ocean and grown in small tanks and fed a dry feed until they weigh about one fifth of an ounce. They are then moved to larger tanks or pond systems and given feed pellets until they reach appropriate weights for harvest. The biggest problem facing production of Japanese Eels is disease; circulation of water and treatment with antibiotics or pharmaceuticals ensures the eels stay healthy.

This has been On the Ocean, a program made possible by the Department of Oceanography and a production of KAMU-FM on the campus of Texas A&M University in College Station. For more information and links, please go to and click “On the Ocean”.

Script Author: Bethany Rawlinson

Editor: James M. Fiorendino

Contributing Professor: Dr. Lisa Campbell

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