Nile tilapia is the second most widely farmed fish globally, with intensive production systems raising significant welfare concerns about crowding, sex manipulation, and disease.
Nile tilapia welfare concerns in intensive production include the use of methyltestosterone to produce all-male populations, a hormone treatment with potential environmental and welfare implications. Chronic crowding causes subordinate fish to experience persistent social stress, leading to immunosuppression and disease susceptibility. Streptococcus agalactiae outbreaks cause severe neurological disease, with affected fish showing abnormal swimming behaviour suggesting significant welfare compromise. Water quality management, particularly dissolved oxygen and ammonia, is critical to tilapia welfare. Developing species-appropriate welfare assessment tools for tilapia is an urgent need given the scale of global production.