Rainbow trout are among the most widely farmed fish in temperate regions. Raceway production systems create specific welfare challenges related to water quality, density, and handling.
Trout welfare in raceway production depends on stocking density, water quality, and handling frequency. High densities cause chronic social stress, increased aggression, and fin injuries that may become infected. Handling during size grading, vaccination, and harvest causes acute stress responses including elevated cortisol. Trout show avoidance responses to poor water quality and prefer cleaner water when given a choice, indicating they can assess environmental conditions relevant to their welfare. Feed management practices that avoid chronic hunger while preventing overfeeding contribute to welfare through sustained good body condition. Certification standards increasingly include behavioral welfare assessments alongside water quality parameters.