November 04, 2020
January 11, 2022

Anago Sushi

アナゴすし

Salt-water Eel

Photography of Anago Sushi

What is Anago (Salt-water Eel)?

In Japanese, the term “anago“ refers to sea or saltwater eels belonging to the genus Congridae. In a culinary context, the collective term anago regularly refers, among other conger eels, to the white-spotted conger eel, whose Japanese name is maanago, which translates as “true conger eel“.

Anago as Ingredient for Sushi or Sashimi

Anago is counted among the traditional representatives of the cooked sushi ingredients (nimono-dane). Therefore, prepared anago sushi is also often called ni-anago-sushi (煮穴子寿司). The broth that results from cooking the anago meat is boiled down, refined, and then used to glaze the meat. This tasty salty sweet sauce is called nitsume (煮詰め) and is an essential part of the taste experience when eating anago nigiri sushi.

The meat is so soft that it almost falls apart and offers a full-bodied sweet taste. The texture is extremely pleasant and melts on the tongue. Anago harmonizes very well with vinegared sushi rice and is traditionally preferred over freshwater eel (unagi) for the preparation of sushi. In contrast to unagi, aanago is less greasy, sweeter and has a finer taste.

Nitsume (煮詰め)


Nitsume or short tsume (つめ), is the golden brown colored sauce with which anago is glazed. It plays a central role in the process of preparation anago sushi and is decisive for the quality of the taste. Tsume is a thick sauce that is created by boiling down the broth from anago. The addition of the ingredients can vary and depends on the preferences of the cook. Most basic recipes consist of the anago broth left over from the preparation, some bones and heads, alcohol, sugar and soy sauce. The skillful balancing of the ingredients gives the tsume a sweet and spicy taste. Traditional or sophisticated restaurants often make them according to a personal, usually secret, recipe and prepare them from scratch each time. In inexpensive restaurants, industrially produced tsume is mainly used. When serving anago nigiri sushi, the sauce should not be poured or drizzled over the meat, but applied as a thin glaze with a brush.

Best Season


The best season for anago is during summertime. It is particularly tasty from July to August, when the fat content is at its highest and the taste is at its fullest. The rest of the year they are also very tasty, so that they can be enjoyed all year round.

Anago Trivia

The toxin extracted from eel blood serum was used by Charles Richet in his Nobel Prize winning research, in which he discovered anaphylaxis [Dujardin-Beaumetz, 1886].

Characteristics & Ecology of Anago (Salt-water Eel)

Anago eels are predominantly nocturnal and start to search for prey at dusk. As carnivores, they feed mainly on small fish, crustaceans, mollusks, and small cephalopods. During the day, they hide in the sandy mud or in the crevices on the seabed. The species that live on the sandy muddy bottom form groups and stretch their heads or even half of their bodies out of their burrows into the sea. The body shape of Anago is elongated and cylindrical, the absence of scales is typical for the species. Adult specimens vary in length from about 30 cm to over 1 m, depending on the species. The distribution area ranges from tropical to temperate seas worldwide.

The family of the Congridae can be divided into three subfamilies:

  • Chin-anago (チンアナゴ) (lat. Heterocongrinae)
  • Honmedama-anago (ホンメダマアナゴ) (lat. Bathymyrinae)
  • Kuro-anago (クロアナゴ) (lat. Congrinae)

Toxic blood


The blood of the anago contains dinogunellin (ichthyotoxin), which is poisonous to humans and has a blood-dissolving effect. Even small doses can cause severe gastreological problems, nervous system disorders and pain. During preparation, care must be taken that the poison does not get into contact with mucous membranes, eyes or open wounds. The toxin is inactivated by sufficient heating above 70°C or 158° F [Davidek, 2018], [Velisek et al., 2020].

Economy

Comparatively few conger eels species are actively fished, but mostly end up as bycatch in the nets of industrial fisheries. A sustainable method is to catch them using special traps. These traps consist of tubes or hoses in which a potential prey is prepared. The traps are constructed in such a way that they taper off from the inlet. If a conger eel tries to get to the prey, it cannot leave the tube after passing the narrowing and can be collected by the fisherman.

Japan consumes more than 70 percent of the world's eel catch, with about half coming from China, South Korea and Taiwan.

Beast Season for Anago

Kaup's cut-throat eel irako-anago
Origin: Pacific
Source: みやぎの食材カレンダー水産物 編 (engl. Miyagi's Food Calendar: Marine Products Edition). 宮城県 農政部 食産業振興課 Miyagi Prefectural Government. 2018.
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Salt-water eel anago
Origin: Pacific
Source: 旬カレンダー (engl. Seasonal Calendar). 株式会社新兵衛、東京. 2006.
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Whitespotted conger maanago
Origin: Pacific
Source: あなごの旬 (engl. Season of Anago). 株式会社クリエ14. https://k52.org/syokuzai/211. Retrieved online on January 15, 2022.
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Depending on preferences, summer is considered the best time to eat anago when the fat content is low because it is considered refreshing, but many people prefer October to December when the fat content is high.
Anago sushi on a white plate. 
				Dennis Schilder. 
				Anago Sushi at Sushi Zanmai Yurakucho. 
				
				copyright ©.
Two pieces of anago sushi on a japanese style plate. 
				Alpha. 
				Anago - Shira Nui AUD5.50 each. 
				flickr.com. 
				Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0).

Further information on the author can be found in the section on image credits.

Video about Anago

External video embedded from youTube.com: Kirikosushi. Anago, Sea eel. Kiriko sushi Sawtelle Los Angeles. Ken Namba

Warnings Regarding Anago Sushi or Sashimi

  1. DINOGUNELLIN: The blood of this seafood contains ichthyohemotoxin, which is toxic to humans and mammals. Consumption of larger amounts of blood can lead to death. In addition, contact with blood can trigger local inflammatory reactions, swelling or ocular sympathies, among other things. Caution is therefore required when handling raw meat. In order for the poison to lose its effect, the meat must be completely cooked at high temperature. [FDA, 2020]

Species of Anago

The following species are regarded as authentic. Either historically, according to the area of distribution or according to the common practice in today's gastronomy:

Japanese Name
Common Names, Scientific Name
anago, maanago
アナゴ、マアナゴ
whitespotted conger
Conger myriaster
family: Congridae
goten-anago
ゴテナナゴ
silvery conger, silvery conger
Ariosoma meeki
family: Congridae
hana-anago
ハナアナゴ
dark-finned conger-eel, darkfin conger, silvery conger
Ariosoma anago
family: Congridae
kiri-anago
キリアナゴ
ash-colored conger eel, ashen conger-eel, black-edged conger
Conger cinereus
family: Congridae
kuro-anago
クロアナゴ
beach conger
Conger japonicus
family: Congridae
nisetsu-maguro-anago
ニセツマグロアナゴ
longnose conger
Bathycongrus wallacei
family: Congridae

The following species can be considered subsitutes. Either on the basis of genetic relationship or because they are similar in taste or appearance:

Japanese Name
Common Names, Scientific Name
irako-anago
イラコアナゴ
gray's cutthroat, kaup's arrowtooth eel, kaup's cut-throat eel
Synaphobranchus kaupii
family: Synaphobranchidae
maru-anago
マルアナゴ
punctuated snake-eel
Ophichthus remiger
family: Ophichthidae
yoroppa-anago
ヨロッパアナゴ
European conger
Conger conger
family: Congridae

References & Further Reading

  • [Dancyu, 2019]: 「㐂寿司」の門外不出のツメづくりに密着 (engl. A Close Look at the Secret Process of Making Tsume-dzukuri at "Kizushi"). dancyu.jp, President Inc. (株式会社 プレジデント社). 2019. https://dancyu.jp/read/2019_00002196.html. Retrieved online on December 24, 2020.
  • [Davidek, 2018]: Jiri Davidek. Natural Toxic Compounds of Foods. CRC Press, Taylor & Francis Group, Boca Raton. 2018.
  • [Dujardin-Beaumetz, 1886]: Dujardin-Beaumetz, E.P. Hurd (transl.). Diseases of the Stomach and Intestines: A Manual of Clinical Therapeutics for the Student and Practitioner. William Wood & Company, New York. 1886.
  • [FDA, 2020]: Fish and Fishery Products Hazards and Controls Guidance. U.S. Department of Health and Human Services Food and Drug Administration Center for Food Safety and Applied Nutrition. 2020.
  • [Heiter, 2007]: Celeste Heiter. The Sushi Book. Things Asian Press. 2007.
  • [Luber & Cohen, 2019]: Marc Luber, Brett Cohen. Stuff Every Sushi Lover Should Know. Quirk Books, Philadelphia. 2019.
  • [Masui & Masui, 2004]: Kazuko Masui, Chihiro Masui. Sushi Secrets. Hachette Illustrated, London. 2004.
  • [Tjandraningsih, 2013]: Christine T. Tjandraningsih. Indonesia eel hot item for smugglers. japantimes.co.jp, The Japan Times, News2u Holdings Inc., Tokyo. 2013. https://www.japantimes.co.jp/news/2013/07/29/national/indonesia-eel-hot-item-for-smugglers. Retrieved online on December 24, 2020.
  • [Tsuchida et al, 2020]: 美登世 土田、潤 髙橋、秀美 佐藤. すしのサイエンス:おいしさを作り出す理論と技術が見える (engl. The Science of Sushi: Seeing the Theory and Technology Behind the Deliciousness of Sushi). Sibundo Shinkosha (誠文堂新光社), Tokyo (東京). 2020.
  • [Velisek et al., 2020]: Jan Velisek, Richard Koplik, Karel Cejpek. The Chemistry of Food. John Wiley & Sons, Chichester. 2020.

Image Credits

  1. Dennis Schilder. Anago Sushi at Sushi Zanmai Yurakucho. License: copyright ©.

  2. Alpha. Anago - Shira Nui AUD5.50 each. flickr.com. License: Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0). Changes made: image quality, brightness, contrast, colour matching, sharpening, cropping.

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