The nutritional composition of salmon feed directly affects fish welfare, growth, and environmental sustainability. Shifting from fishmeal-based to alternative protein feeds has welfare and ecological implications.
Salmon diet quality has direct welfare implications. Nutritional deficiencies — particularly in essential fatty acids, vitamins, and minerals — compromise immune function and increase disease susceptibility. Cataract development, which affects a significant proportion of farmed salmon at high densities, has been linked to dietary deficiencies in histidine and riboflavin. Skeletal deformities including vertebral compression are associated with nutritional imbalances during early development. The shift from fishmeal to plant proteins has introduced new welfare challenges — some plant ingredients contain anti-nutritional factors that impair gut function and immune status. Soybean meal causes enteritis in salmon at high inclusion rates. Insect meal (black soldier fly larvae) shows promise as a nutritionally complete, welfare- and environment-friendly alternative to both fishmeal and soy.