Wrasse and lumpfish are used as biological sea lice controllers in salmon farming, but their welfare has received little attention despite growing evidence of sentience and significant welfare challenges in this role.
Wrasse and lumpfish introduced to salmon sea cages face multiple welfare challenges: exposure to extreme salmon crowding during husbandry operations, lack of hiding structures in open-water cages, temperature and salinity challenges, and disease. Mortality rates are high. Little is known about the welfare needs of these species in captive settings because they have been treated as tools rather than animals. As evidence for fish sentience strengthens, the welfare status of cleaner fish — used and largely discarded by an industry that creates the sea lice problem they are used to solve — deserves urgent attention.