<p>This book provides a comprehensive examination of the role of <i>Bacillus</i> bacteria in aquaculture, particularly focusing on finfish and shellfish. It begins with foundational chapters on the anatomy and physiology of these aquatic species, their immune systems, and the biology of Bacillus bacteria. The book discusses the specific interactions between <i>Bacillus</i> and the gastrointestinal tracts of fish and shellfish, examining the production and effects of <i>Bacillus</i>-derived exoenzymes and bacteriocins and their role in enhancing aquatic health and water quality. Additionally, the book covers the role of <i>Bacillus</i> in bioremediation, particularly in improving water quality, which is a significant concern in aquaculture. The latter sections delve into the application of <i>Bacillus</i> as probiotics and paraprobiotics in fish and shellfish culture, their integration in feed biotechnology, and a critical evaluation of their safety. The book concludes with a critical d