Eels are elongated fish, ranging in length from five centimetres (2 in) to four metres (13 ft).^[1] Adults range in weight from 30 grams to over 25 kilograms. They possess no pelvic fins, and many species also lack pectoral fins. The dorsal and anal fins are fused with the caudal or tail fin, forming a single ribbon running along much of the length of the animal.^[2] Most eels live in the shallow waters of the ocean and burrow into sand, mud, or amongst rocks. A majority of eel species are nocturnal and thus are rarely seen. Sometimes, they are seen living together in holes, or "eel pits". Some species of eels live in deeper water on the continental shelves and over the slopes deep as 4,000 metres (13,000 ft). Only members of the family Anguillidae regularly inhabit fresh water, but they too return to the sea to breed.^[3]

Eel blood is poisonous to humans^[4] and other mammals,^[5][6][7] but both cooking and the digestive process destroy the toxic protein. The toxin derived from eel blood serum was used by Charles Richet in his Nobel Prize-winning research, in which Richet discovered anaphylaxis by injecting it into dogs and observing the effect.

The Jewish laws of kashrut forbid the eating of eels.^[8] Similarly, according to the King James Version of the Old Testament, it is acceptable to eat fin fish, but fish like eels are an abomination and should not be eaten.^[9]

Japan consumes more than 70 percent of the global eel catch.^[10]

Freshwater eels (unagi) and marine eels (anago, conger eel) are commonly used in Japanese cuisine; foods such as unadon and unajuu are popular but expensive. Eels are also very popular in Chinese cuisine and are prepared in many different ways. Hong Kong eel prices have often reached 1000 HKD per kilogram and once exceeded 5000 HKD per kilogram. Eel is also popular in Korean cuisine and is seen as a source of stamina for men.^{[citation needed]} The European eel and other freshwater eels are eaten in Europe, the United States, and other places. Traditional east London foods are jellied eels and pie and mash, although their demand has significantly declined since World War II. In Italian cuisine eels from the Valli di Comacchio, a swampy zone along the Adriatic coast, are especially prized along with freshwater eels of Bolsena Lake.^{[citation needed]} Eels are popular in the cuisines of Northeast India.^{[citation needed]} Freshwater eels, known as kusia in Assamese, are eaten with curry,^[11] often with herbs.^[12]

Locality	Type	Image	Description
England	Jellied eels		Jellied eels originated in 18th century England, mainly in the East End of London. The dish consists of chopped eels boiled in aspic stock that is allowed to cool and set, forming a jelly. It is eaten cold.
Belgium	Paling in 't groen ("Eels in the green")		Specialty of the Brussels – Dendermonde – Antwerp area. Freshwater eels cut to about 5 cm (2 in) pieces, cooked in green herb sauce. Usually served hot, either as hors-d'œuvre or with Belgian fries or bread; but can also be eaten cold.
Japan	Unagi		Unagi is the Japanese word for freshwater eels, especially the Japanese eel. Saltwater eels are known as anago. Unagi are a common ingredient in Japanese cooking.
	Kabayaki		Kabayaki is a typical preparation of the unagi eel in Japan.,[13] sometimes extended to preparation of other fish,[14][15] where the fish is split down the back[14] (or belly), gutted and boned, butterflied, cut into square fillets, skewered, dipped in a sweet soy sauce-base sauce before broiled on a grill.
	Unadon		Unadon, lit. "eel bowl", consists of a donburi type large bowl filled with steamed white rice, and topped with fillets of eel grilled in the kabayaki style, similar to teriyaki.
Korea	Jangeo-gui		Jangeo-gui is a gui (grilled dish) made with marinated and grilled freshwater eels.
Vietnam	Miến lươn		Miến lươn is cellophane noodle soup with eel, which is deep-fried or stir-fried, topped with bean sprout, wood ear, onion and coriander. It is a delicacy in Northern Vietnam, especially Hanoi.
	Xúp lươn		Xúp lươn, lit. eel soup, is a soup dish made from eel or pork broth, consisting eels stir-fried with chive, onion, annatto and chilli powder. It is often served with bánh mì or bánh cuốn. This dish is a speciality in Nghe An province.
Widespread	Elvers		Elvers are young eels. Traditionally, fishermen consumed elvers as a cheap dish, but environmental changes have reduced eel populations. Similar to whitebait, they are now considered a delicacy and are priced at up to 1000 euro per kilogram.[16] The Spanish angulas consists of sautéd elver in olive oil, garlic and a chili pepper. In Spain, these angulas are now rare and very expensive (a small serving of angulas can cost the equivalent of US$100 or more). There are also imitation angulas which can be purchased cheaply made of surimi.
	Smoked eel		Smoked eel is considered a delicacy in many localities, such as northern Germany, the Netherlands, the Czech republic, Poland, Denmark and Sweden.

Eels are a Priority Species under the UK Post-2010 Biodiversity Framework. The European eel (Anguilla anguilla) is listed as Critically Endangered on the global IUCN Red List of Threatened Species. While the Japanese eel (Anguilla japonica) and American eel (Anguilla rostrata) are assessed as Endangered.^[17]

In 2010, Greenpeace International added the American eel, European eel, and Japanese eel to its seafood red list. "The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries."^[18]

The US government deems the commercial eel industry was worth $12 million in Maine in 2017.^[19]

The eel was a cheap, nutritious and readily available food source for the people of London; European eels were once so common in the Thames that nets were set as far upriver as London itself, and eels became a staple for London's poor. The first "Eel Pie & Mash Houses" opened in London in the 18th century, and the oldest surviving shop — M.Manze — has been open since 1902.^[20]

• Eel life history
• Pie and mash

• Hepburn, James Curtis (1888). A Japanese-English and English-Japanese Dictionary (4 ed.). Tokyo: Z.P. Maruya & Company.
• Shinmura, Izuru (1976). Dictionary of the Japanese language (in Japanese). Iwanami Shoten.