Freshwater mussels are among the most endangered animals in the world. The welfare status of bivalve molluscs is contested but increasingly considered in conservation and aquaculture contexts.
Freshwater mussel welfare occupies an uncertain space in animal welfare science. Bivalves lack centralised nervous systems making the likelihood of pain experience lower than for cephalopods or fish. However, they show reflexive responses to noxious stimuli and physiological stress responses that warrant precautionary consideration. The welfare significance of freshwater mussel conservation extends beyond the mussels themselves to the entire freshwater ecosystem: mussels are water quality engineers filtering and clarifying water that benefits all freshwater animals. Their population collapses affect freshwater fish, invertebrates, and dependent wildlife. The welfare of ecologically critical species affects broader welfare outcomes through ecosystem integrity even if individual mussel welfare is uncertain.