Salmon Sea Lice Cleaner Fish Welfare

Wrasse and lumpfish used as biological lice control in salmon aquaculture are themselves fish with welfare needs that are largely overlooked.

Key Facts

Wrasse species (primarily ballan, goldsinny, and corkwing) and lumpfish are deployed in Atlantic salmon sea cages to eat sea lice
Norway deploys hundreds of millions of cleaner fish annually — making them one of the most numerous farmed fish species by count
Wrasse are tropical-origin species used in cold Norwegian waters — many suffer thermal stress and high mortality rates
Cleaner fish welfare standards are absent from most aquaculture welfare frameworks that focus exclusively on the salmon
Mortality rates for cleaner fish in salmon cages can exceed 30-50% per production cycle — an enormous welfare cost
Welfare research for cleaner fish has lagged salmon welfare science by over a decade

Welfare Considerations

Cleaner fish welfare represents a systematic welfare blind spot in salmon aquaculture. The deployment of wrasse and lumpfish as biological lice control has been adopted rapidly as a welfare-positive alternative to chemical treatments — and it may be better for salmon welfare — but the welfare of the cleaner fish themselves has received minimal attention. Wrasse species are deployed in Norwegian waters that are significantly colder than their optimal thermal range, causing stress, immune suppression, and high mortality. Lumpfish face different challenges including predation by salmon and competition for shelter. The scale of cleaner fish deployment — hundreds of millions annually — means that even modest welfare improvements per individual would have enormous aggregate welfare impact. Current best practice guidance from Norwegian welfare bodies is beginning to address cleaner fish welfare, but standards remain underdeveloped.

What You Can Do

Support aquaculture welfare organisations that advocate for cleaner fish welfare alongside salmon welfare
Advocate for cleaner fish welfare requirements to be incorporated into salmon aquaculture certification schemes
Support research into optimal cleaner fish deployment conditions including thermal tolerance and shelter provision
Back investment in non-biological sea lice control that reduces reliance on large numbers of cleaner fish
Choose salmon from producers who publish cleaner fish mortality data as part of their welfare transparency reporting