Carp aquaculture is the world's largest freshwater fish farming sector, with welfare concerns around stocking density, handling stress, and slaughter practices.
Carp pond harvesting typically involves progressive crowding as ponds are drained, causing severe hypoxia and distress as dissolved oxygen falls. Fish pile onto each other in decreasing water volume, and may be transported alive for extended periods in crowded conditions before slaughter by live chilling or ice bath - methods that can take many minutes to cause unconsciousness in cold-tolerant species. The scale of carp production - billions of individuals annually - means welfare improvements, even modest ones, would benefit an enormous number of sentient animals.