Dissolved oxygen levels in fish farms directly affect welfare, with low oxygen causing chronic stress, impaired immune function, and suffocation. Proper management is fundamental to basic fish welfare.
Dissolved oxygen management sits at the intersection of fish welfare and aquaculture economics. Chronic hypoxia causes suffering that is invisible to observers but profound for fish: labored breathing, impaired cognition, and physiological stress that compromises immune function and growth. Mass mortality events from oxygen depletion cause acute suffering at enormous scale. Yet adequate oxygen monitoring and aeration technology exists and is affordable relative to production costs. The barrier is often awareness and implementation quality rather than technology. Regulatory standards that require minimum oxygen levels and continuous monitoring would prevent some of the most severe welfare outcomes in aquaculture.