European and Japanese eels are farmed extensively for sushi and other markets, yet their welfare in aquaculture settings receives almost no scientific or regulatory attention despite evidence of significant pain sensitivity.
Farmed eels represent a concentrated welfare problem at multiple points: capture of wild glass eels causes stress and injury; farm conditions involve high density and barren environments; and slaughter methods are among the least humane of any commercial fish species. The dependence on wild glass eel collection means that every farmed eel has already experienced the welfare stress of capture and transport. In farm conditions, eels' natural burrowing and hiding behavior is entirely suppressed in bare raceway tanks. Slaughter by cutting or ice-water bathing causes prolonged suffering before death. The combination of critical endangerment in the wild and poor welfare in captivity makes eel farming one of the most ethically problematic sectors of aquaculture.