Farmed Salmon Lice and Cleaner Fish Welfare

The use of wrasse and lumpfish as biological sea lice control in salmon farming raises welfare questions about the cleaner fish themselves, who are often raised and deployed under inadequate conditions.

Key Facts

Approximately 50 million cleaner fish — primarily ballan wrasse and goldsinny wrasse — are deployed in Norwegian salmon cages annually
Lumpfish (Cyclopterus lumpus) are increasingly used; production exceeded 30 million per year by 2022
Wrasse naturally live in kelp forest habitats; salmon cage conditions with no structure or shelter create chronic stress
Cleaner fish mortality in salmon cages is estimated at 50-80% within the first year of deployment — extremely high welfare and economic costs
Cleaner fish are often not removed before salmon are treated with chemical bath treatments; treatment chemicals are toxic to cleaner fish
Wrasse require live food; salmon farm pellet diets are nutritionally inadequate, causing chronic nutritional stress
Best practice guidelines for cleaner fish welfare have been developed by Norwegian and UK aquaculture bodies but compliance is inconsistent
Wrasse can live 15-20 years in the wild; those in salmon cages rarely survive a full production cycle

Welfare Considerations

Cleaner fish welfare is a second-order welfare problem created by the first-order welfare problem of sea lice in salmon farming. Deploying wrasse and lumpfish as biological pest control introduces millions of additional animals into production systems whose needs are fundamentally incompatible with the cage environment. Wrasse are habitat specialists that evolved in structurally complex kelp forests; an open salmon cage provides none of the shelter, territory, or substrate they require for normal behavior and physiological function. The 50-80% annual mortality rate reflects systematic welfare failure. Improving cleaner fish welfare requires habitat provision within salmon cages, nutritionally adequate feeding, protection from chemical treatments, and honest assessment of whether biological control can ever meet these species needs in the salmon cage context.

What You Can Do

Support aquaculture certification schemes that include cleaner fish welfare standards in their salmon audit criteria
Advocate for mandatory cleaner fish welfare requirements in aquaculture regulations in major salmon-producing countries
Support research into non-biological sea lice control methods that reduce or eliminate cleaner fish deployment
Reduce farmed salmon consumption or choose certified producers who demonstrate both salmon and cleaner fish welfare