Metazoan parasites are among the most problematic diseases affecting fish mariculture. Current chemical treatment methods are unsustainable and coming under increased environmental regulation. More holistic management methods are needed for the sustainable future of fish mariculture. Major parasites include acanthocephalans, nematodes, trematodes, and crustaceans, which can cause significant economic losses and animal welfare issues. Effective long-term control requires moving beyond reactive chemical treatments.