Using cleaner fish like wrasse and lumpfish to control sea lice reduces chemical treatment burden but raises welfare concerns for the cleaner fish themselves.
Cleaner fish deployed in salmon cages face welfare challenges including predation by salmon, starvation when sea lice levels are low, and extreme mortality from diseases. The welfare improvement for salmon from reduced sea lice burden may be offset by significant welfare harm to cleaner fish. Developing welfare standards for cleaner fish and exploring alternative biological control methods is essential for this approach to represent genuine welfare improvement.