Rainbow trout is one of the most important farmed freshwater fish, with welfare challenges from high stocking densities, disease, and suboptimal handling practices.
Rainbow trout welfare is affected by high stocking density causing social stress and reduced swimming freedom, temperature-related disease outbreaks, and injury from equipment during grading and harvest. Trout show strong preferences for lower stocking densities when given a choice, indicating that welfare is compromised in intensive systems. Disease outbreaks cause chronic welfare harm across affected populations. Percussive stunning before slaughter is effective and represents current best practice. Improvements in water quality monitoring and disease prevention significantly benefit individual trout welfare.