Aquaculture, being the fastest growing food producing industry in the world, is looked upon for alleviating the malnutrition especially among the under privileged population. However, intensive aquaculture practices have led to increased incidences of diseases and significant production losses. Among various health management measures employed in aquaculture, vaccination has been proven to be the best approach to protect fish against pathogens. It is considered to be safe and is a key factor for sustainable aquaculture. In this background, apart from the basic understanding of fish and shellfish immune system, updated knowledge on various types of vaccines and the vaccination strategies currently employed in aquaculture are also covered. The book is designed to provide the latest and comprehensive knowledge on all these aspects as a compiled resource material which is useful to students, researchers and other professionals in the field of aquaculture.