Cleaner Fish Welfare: Balancing Sea Lice Control and Wrasse Wellbeing

Wrasse and lumpfish are deployed in salmon cages as biological control for sea lice. Their welfare has received increasing attention as their numbers scale to millions annually.

Key Facts

An estimated 50 million cleaner fish were deployed in Norwegian and Scottish salmon farms in 2022
Wrasse species used include corkwing, goldsinny, rock cook, and ballan wrasse
Lumpfish (Cyclopterus lumpus) are also widely used and are hatchery-produced at scale
Cleaner fish mortality rates in salmon cages can exceed 50% annually from disease, predation, and starvation

Welfare Considerations

Cleaner fish welfare is an emerging priority — these small fish are exposed to the same pathogens as salmon (including Caligus and Lepeophtheirus sea lice) and often receive less veterinary attention and monitoring. Lumpfish mortality from bacterial diseases including vibriosis is extremely high in some farms. Wrasse require shelter structures and appropriate substrate within cages, and may suffer from exposure to high-light conditions. The welfare cost of biological lice control must be weighed against the welfare benefit of reduced lice burden in salmon.

What You Can Do

Support research into improving hatchery conditions and disease resistance for cleaner fish
Advocate for mandatory cleaner fish welfare monitoring as part of salmon farm aquaculture licences
Choose salmon from farms with published cleaner fish welfare protocols and mortality data
Encourage development of alternatives to biological lice control that reduce cleaner fish numbers required