Cleaner Wrasse Welfare in Salmon Farming: The Fish That Clean Other Fish

Cleaner wrasse and lumpfish are used as biological sea lice control in salmon farming, but their welfare as working fish in an environment for which they are poorly adapted is an emerging concern in aquaculture welfare science.

Key Facts

Approximately 50 million cleaner wrasse and lumpfish are deployed annually in Norwegian salmon farms for biological lice control
Cleaner wrasse mortality rates in salmon farms average 50-80%, far higher than salmon in the same systems
Cleaner fish are wild-caught or farmed with limited welfare standards compared to salmon production fish
Lumpfish are better adapted to cold Norwegian waters than tropical wrasse species, with lower mortality rates
Cleaner fish welfare needs including shelter, appropriate food, and species-typical behaviour are often unmet in salmon cages
Welfare standards specifically for cleaner fish are now being developed by Norwegian regulators for the first time

Welfare Considerations

Cleaner fish welfare represents a blind spot in salmon aquaculture welfare because they are used as tools rather than treated as animals with their own welfare interests. Wild-caught wrasse removed from their natural reef environments and placed in open-water salmon cages experience profound environmental mismatch. Their high mortality rates — often exceeding 50% per deployment — indicate that the systems they are placed in are poorly suited to their welfare needs. The irony of using poorly-welfare-managed cleaner fish to improve the welfare of better-managed salmon requires acknowledgment and resolution through species-appropriate cleaner fish husbandry standards.

What You Can Do

Support aquaculture welfare certification schemes that are developing and enforcing cleaner fish welfare standards
Ask salmon retailers whether their suppliers have cleaner fish welfare requirements in their certification criteria
Advocate for Norwegian and Scottish aquaculture regulators to finalise and enforce cleaner fish welfare legislation
Support research into alternative sea lice management that reduces dependence on biological control using cleaner fish