Wrasse and lumpfish deployed as cleaner fish in salmon farms to remove sea lice face significant welfare challenges that are receiving growing scientific and regulatory attention.
Cleaner fish welfare represents a paradox in salmon aquaculture welfare improvement: using one group of fish as a welfare solution for another group while creating welfare problems for the first group. The scale is enormous; tens of millions of lumpfish and wrasse are deployed annually, with high mortality indicating that many suffer significantly before dying. The conditions in salmon cages, including temperature fluctuations, crowding, and competition for food with much larger salmon, are stressful for cleaner fish species. Regulatory frameworks for salmon welfare increasingly require welfare considerations for cleaner fish, but implementation of meaningful standards is at an early stage. The fundamental question of whether it is acceptable to impose suffering on one sentient species to reduce suffering in another requires ethical as well as practical resolution.