Aquaculture

Farmed Rainbow Trout Crowding Welfare

Stocking density in rainbow trout farms strongly influences welfare through its effects on stress, aggression, and disease susceptibility.

Key Facts

Rainbow trout are commonly farmed at densities of 25 to 80 kg per cubic meter
High density causes chronic cortisol elevation, suppressed immune function, and fin damage
Fin erosion is a visible welfare indicator that worsens with increasing stocking density
Lower densities improve growth rates, disease resistance, and behavioral normality
Legal stocking limits vary widely between countries and many have no upper limit

Welfare Considerations

Rainbow trout at high stocking densities experience chronic physiological stress that compromises every aspect of their health and behavioral expression. Reducing stocking density is the single most impactful welfare improvement available.

What You Can Do

Choose trout from farms with certified stocking density limits below 25 kg per cubic meter
Advocate for legally binding stocking density limits in rainbow trout aquaculture
Support research establishing evidence-based stocking density thresholds for trout welfare