Lumpfish are used as biological pest controllers in salmon farming to eat sea lice. Their own welfare needs are largely overlooked despite being kept in challenging conditions with high mortality rates.
Lumpfish represent one of aquaculture's most significant hidden welfare problems. These small fish are produced in hatcheries and deployed in salmon sea cages as biological sea lice controls - a role that benefits salmon welfare but comes at high cost to the lumpfish themselves. Mortality rates above 50% within a year of deployment indicate that sea cage conditions are profoundly unsuitable for lumpfish welfare. The high mortality is attributable to poor adaptation to cage conditions, rough handling at deployment, predation by salmon and inadequate access to appropriate food. Using one species to improve another's welfare while ignoring the first species' welfare entirely is ethically inconsistent and should be addressed by welfare standards that cover all species in aquaculture systems.