What farmed fish are fed has profound implications for both their welfare and the sustainability of the global food system. The shift away from wild-caught fishmeal is gathering momentum but raises complex trade-offs.
Feed is foundational to fish welfare in aquaculture. Nutritional deficiencies cause specific welfare harms: vitamin deficiencies cause cataracts that impair vision in salmon; amino acid imbalances affect growth and immune function; inadequate omega-3 levels compromise neurological development. The pressure to reduce reliance on wild-caught forage fish — which have their own welfare status as sentient animals — must be balanced against ensuring alternative feeds fully meet farmed fish nutritional needs. Welfare-conscious feed development requires longitudinal research into the effects of novel ingredients on fish health indicators. The most welfare-positive feed systems will eventually source protein from non-sentient or lower-sentience organisms while fully meeting fish nutritional requirements.