European and Japanese eels are critically endangered and widely farmed, with welfare research severely lagging behind the scale of production and the complexity of their biology.
Eel welfare represents a convergence of conservation and welfare concerns that receive inadequate attention proportionate to their severity. The European eel's critical endangerment means that every eel farmed involves a wild-caught glass eel removed from an already depleted population. The welfare of farmed eels is poorly researched, yet behavioral responses to noxious stimuli suggest meaningful pain experience. High-density eel farming with poor water conditions causes chronic welfare compromise. The most welfare-positive approach would combine wild population protection with development of captive breeding to eliminate wild capture dependence — a technically difficult but necessary goal for both welfare and conservation.