European and Japanese eels are heavily farmed and heavily threatened in the wild, yet their welfare in aquaculture has received minimal research attention.
Eel aquaculture presents a compound welfare problem: the species is poorly studied from a welfare perspective, relies on wild-caught juveniles that threatens the species further, and is kept in conditions with known welfare deficiencies. Like other fish, eels experience pain and show stress responses to poor water quality and high density. Their elongated body and slippery surface creates handling challenges that often result in rough treatment during grading and transfer. The reliance on wild glass eels means aquaculture demand contributes to wild population decline — a welfare problem at population level beyond individual animal suffering. Precautionary welfare standards and reduced consumption pressure on this threatened species are both warranted.