Wrasse and lumpfish are deployed in salmon farms as biological sea lice control agents. These 'cleaner fish' are themselves sentient animals whose welfare needs are frequently neglected in commercial aquaculture operations.
The use of cleaner fish as biological sea lice control creates a welfare paradox: one sentient species is sacrificed to reduce suffering in another. Wrasse and lumpfish have complex nervous systems, show learning and memory, and experience physiological stress. Their welfare in salmon farms is typically poor: they are often inadequately fed, provided with insufficient shelter, subjected to the stresses of the salmon farming environment and exposed to salmon-specific pathogens for which they have no immunity. Improving cleaner fish welfare requires treating them as animals with welfare needs in their own right rather than as disposable biological tools.