Rainbow trout are one of the most commonly farmed fish globally, with specific welfare challenges that are increasingly well-understood.
Rainbow trout welfare in aquaculture is better understood than most fish species, partly because they are easily studied and partly because welfare and quality metrics align. Fin erosion — caused by crowding, inadequate flow, and aggressive behaviour — provides a visible welfare proxy. Pre-slaughter welfare matters directly for both fish welfare and product quality: stressed fish have elevated lactic acid, affecting flesh pH and texture. The commercial alignment creates unusual incentive for welfare investment in trout farming compared to lower-value species.