Pre-harvest fasting of farmed fish is used to empty gut contents before processing, but prolonged fasting causes measurable physiological stress and welfare harm that can be minimized through optimized fasting protocols.
Pre-harvest fasting is a routine welfare cost in aquaculture that is often longer than necessary for its stated purpose of gut clearance. Fish in extended fasting experience hunger and associated stress that accumulates over the fasting period. Optimized protocols that achieve gut clearance with the minimum effective fasting time reduce welfare harm without compromising food safety objectives. This is a case where welfare improvement aligns directly with economic efficiency — shorter fasting reduces fish stress and mortalities during holding.