Aquaculture Cleaner Fish Welfare: Wrasse and Lumpfish Used for Sea Lice

Wrasse and lumpfish are used as biological sea lice control in salmon farming, but their own welfare is frequently overlooked. These small fish face significant stress and mortality in production and deployment.

Key Facts

Cleaner fish — primarily wrasse species and lumpfish — are added to salmon cages to eat sea lice from salmon skin
An estimated 50 million cleaner fish are deployed in Norwegian and Scottish salmon farms annually
Wrasse and lumpfish mortality in cages can be extremely high — losses of 50-80% per deployment cycle are documented
Wrasse are territorial reef fish with complex social structures — cage deployment ignores these behavioural needs entirely
Lumpfish do not thermoregulate effectively and may suffer in warm summer water temperatures in Norwegian cages
Cleaner fish welfare has received almost no research attention relative to their numbers and likely welfare burden

Welfare Considerations

Cleaner fish represent a hidden welfare problem within an industry focused on improving salmon welfare: in deploying wrasse and lumpfish to address sea lice (itself a welfare problem), the industry has created a new welfare problem affecting different fish in vast numbers. Wrasse are complex reef-associated fish with home territories, social relationships, and specific shelter needs — none of which a salmon cage provides. Lumpfish are benthic (bottom-dwelling) animals that navigate poorly in the open water of salmon cages. Both species face crowding with salmon vastly larger than themselves, competition for food, inability to escape conflict, and vulnerability to cold-water shock or hyperthermia depending on season and location. The welfare calculation of cleaner fish use — whether the sea lice reduction benefit to salmon is worth the welfare cost to cleaner fish — has not been seriously conducted. As the numbers suggest, this is a significant welfare issue affecting tens of millions of sentient animals.

What You Can Do

Support research into cleaner fish welfare — it is dramatically under-resourced relative to cleaner fish deployment numbers
Advocate for aquaculture welfare standards to explicitly include cleaner fish welfare requirements alongside salmon welfare
Support development of alternatives to biological sea lice control that do not involve live cleaner fish deployment
Ask salmon certification schemes whether their standards address cleaner fish welfare — most currently do not
Support RAS-based salmon production that eliminates the sea lice problem and thus the need for cleaner fish entirely