Diseases are a major threat to the sustainability of the aquaculture industry, but using antibiotics to treat diseases presents some drawbacks. In this text, 25 specialists from the U.S. and Canada contribute 17 chapters on nutrition as an alternative means of improving fish health and defending against infection. Coverage includes an overview of the diseases of warmwater fish, economically important diseases of salmonids, shrimp viral diseases, marine fish and larval fish nutrition, feeding management, vitamin and mineral requirements, fish immune system mechanisms, immunostimulants, aflatoxins, nutrition and environmental stress, and the use of vaccines.