The feed used in aquaculture - typically containing wild-caught fish - creates a welfare multiplier effect where farmed fish welfare depends on the suffering of billions of wild-caught forage fish.
Aquaculture feed creates a hidden welfare cost: the billions of forage fish caught, processed, and fed to farmed fish. If forage fish are sentient, their capture and processing causes welfare harm at enormous scale. The processing chain for fishmeal involves harvesting, crushing, and cooking fish without welfare considerations. This welfare multiplier means improving farmed fish welfare in isolation does not address the full welfare impact of aquaculture. Feed transitions to insect meal, algal oils, and plant proteins reduce the forage fish burden substantially. Insect meal production itself raises welfare questions about insect sentience - but at far smaller individual scale.