This book explores diverse strategies to combat diseases in aquaculture and effectively manage fish health for sustainable farming practices. It addresses the need for robust diagnostic tools, biosecurity measures, advanced breeding techniques, and innovative vaccine development in aquaculture. Divided into four sections, the first section introduces state-of-the-art diagnostic tools for pathogen detection, including the latest advancements in metagenomics and next-generation sequencing. The second section reviews the application of genetics, breeding, bacteriophage therapy, and nanotechnology as novel approaches to enhance disease resistance. It also explores the genomics of infectious diseases, the application of genetic technologies in combating these diseases, and future breeding strategies for sustainable aquaculture. The third section examines the role of vaccines in maintaining fish health and their potential applications in disease management, focusing on the current status of vaccine development and the challenges. The final section emphasizes the importance of fish welfare, discussing the roles of stress management, food systems, and human activities in promoting fish health. It also presents the role of food systems in sustainable aquaculture and reviews the use of prebiotics, probiotics, and synbiotics to enhance growth performance, immune responses, and disease resistance. This book is intended for researchers and professionals in the fields of aquaculture, marine biology, and sustainable farming practices.