Wrasse and lumpfish added to salmon pens to eat sea lice have their own welfare needs that are often inadequately met. The welfare of cleaner fish deserves the same attention as the salmon they serve.
Cleaner fish welfare represents an emerging welfare frontier in aquaculture. The industry's initial approach was purely instrumental - cleaner fish were seen as living tools for lice management rather than as animals with their own welfare needs. Recognition that wrasse and lumpfish are sentient species has driven development of welfare guidelines and improved husbandry practices. The provision of appropriate shelter, species-appropriate diet, and reduced salmon aggression through pen management all significantly improve cleaner fish welfare and survival. From a welfare system perspective, improving cleaner fish welfare while using them to reduce lice - which themselves cause salmon welfare harm - represents a complex welfare optimization. The long-term solution may be closed containment systems that eliminate lice without requiring any cleaner fish.