Welfare considerations for farmed carp, the most numerically significant farmed fish species globally, including stocking density management, winter mortality, and slaughter practices.
Farmed carp presents a stark example of the relationship between welfare research attention and production volume: carp account for more fish farmed annually than any other species by substantial margin, yet receive a tiny fraction of the welfare research investment directed at salmon. This neglect reflects carp's historical position as a low-value commodity fish in Asian and Eastern European production systems, and assumptions about carp sentience that are increasingly difficult to sustain. Carp demonstrate behavioral and physiological stress responses to crowding, disease, and handling that are consistent with welfare-relevant experience. Winter pond mortality from oxygen depletion — where fish die slowly from hypoxia under ice cover — represents a welfare failure at massive scale that receives virtually no regulatory attention. The traditional Central European practice of live bathtub holding followed by live slaughter for Christmas consumption is a welfare concern that has generated consumer activism in some countries. Improving carp welfare requires the same systematic approach applied to salmon: welfare-informed stocking density standards, disease management protocols that reduce KHV impact, and mandatory pre-slaughter stunning.