Rainbow trout are one of the most widely farmed salmonids globally, and welfare science for this species has advanced significantly in recent years.
Rainbow trout welfare science has benefited from its close taxonomic relationship to Atlantic salmon, where research investment has been greater. Many of the welfare challenges are shared: crowding stress, gill disease, sea lice in marine environments, and pre-slaughter handling. Progressive trout producers have adopted welfare monitoring protocols including regular fin condition and external lesion scoring, water quality optimization, and pre-slaughter stunning. The key welfare improvement opportunities are standardizing stocking density limits with welfare evidence, extending mandatory stunning requirements to trout in all jurisdictions, and developing positive welfare indicators for this species that go beyond absence of disease. Consumer demand for certified trout creates market incentives for producers to invest in welfare.