Lumpfish used as cleaner fish in salmon aquaculture face significant welfare challenges as non-target species in a system designed primarily for salmon production.
Lumpfish welfare in salmon aquaculture has been described as among the worst welfare situations in commercial fish farming. Most lumpfish deployed in salmon cages die within months from starvation, disease, or predation. They are often not fed supplementary food on the assumption they will eat sea lice, but lice availability is insufficient for their nutritional needs. Cataracts, presumed from UV light exposure in surface waters, affect a high proportion. Poor water quality and crowding in salmon cages create a hostile environment for lumpfish. Growing awareness of this welfare problem has driven regulatory action in Norway and Scotland, with new welfare standards for cleaner fish production and deployment increasingly being implemented.