Wrasse and lumpfish are used as cleaner fish in salmon farms to control sea lice. Their welfare has been largely overlooked despite documented mortality rates that raise serious concerns.
The welfare of wrasse and lumpfish used in salmon farming represents a significant and largely invisible welfare problem. These are wild-caught or hatchery-reared fish deployed in an alien environment — a salmon cage — where their behavioral needs are entirely unmet. Wrasse are reef fish requiring complex three-dimensional habitat, invertebrate food, and shelter; salmon cages provide none of these. The 40-60% mortality rates documented in many facilities indicate severe welfare failure. Because cleaner fish welfare is not part of salmon welfare certification, billions of individual animals are dying under avoidable conditions. The paradox is acute: cleaning methods intended to reduce salmon welfare problems cause severe welfare problems of their own. Investment in non-biological lice control — and, where cleaner fish are used, genuine welfare provisions — is urgently needed.