Rainbow trout are among the most extensively researched farmed fish species for welfare, with evidence of pain experience and stress responses informing increasingly sophisticated husbandry standards.
Rainbow trout occupy an important position in fish welfare science as the species for which evidence of pain-relevant experience is strongest and most replicable. Studies demonstrating post-injury hypersensitivity, analgesic seeking and cognitive impairment following painful stimuli in trout have substantially contributed to broader recognition of fish sentience. For farmed trout, this evidence base supports welfare standards addressing water quality, stocking density, handling protocols and slaughter methods. The persistent use of CO2 stunning in trout slaughter despite evidence of distress before unconsciousness represents a significant unresolved welfare challenge in the industry. Consumer preference for welfare-assured trout products creates market pressure that is driving welfare standard development.