Rainbow trout are the most widely farmed salmonid in Europe. Water quality management and welfare indicator monitoring are essential for maintaining good welfare throughout the production cycle.
Rainbow trout welfare in intensive systems depends critically on water quality parameters that can fluctuate rapidly. Hypoxic events cause acute distress and mass mortality; elevated temperatures cause chronic stress that compromises immune function and increases disease susceptibility. Fin damage from aggression at high densities is a reliable indicator of compromised welfare that can be assessed visually. Good stockpersonship that monitors both water parameters and fish behaviour continuously is the foundation of trout welfare.