This book is about relevant recent research topics in understanding aquaculture for practical approaches; aquatic science, engineering, feed and nutrition, immunology and health are reviewed. The book includes information on why certain fish strains differ in disease resistance, all the current data on fish cell populations, the regulation of the response by factors, and the major histocompatibility complex are explained in detail. The book contains the chapters on nutrition, feed and feed additives, ecology, immunology, microbiology, toxicology, biochemistry, nanotechnology, pharmacology, and biotechnology, among other fields of basic and applied research. Over the past era, scientists have recognized the importance of nutrition in maintaining the health of humans and other animal species, including fish. Humans and other terrestrial animals were the focus of previous research on the links between nutrition, immune response, and disease resistance.  However, attempts to conduct similar studies using fish have met with limited success in the last two decades due to a lack of understanding of the immune response in fish. In most facilities, the animals are kept at relatively high densities, causing stress and disease problems are the challenges that we face today and this book opens up the exciting new area of research to truly understand the relationship between fish genetics and immune reactivity. The aquatic immune system turns out to be a crucial reference as aquatic products are increasingly used as model systems for vertebrate immune systems. This book provides that the research students and scientists with a useful text on the latest knowledge of the aquatic feed and nutrition, immune system, cutting-edge technologies, draws everyone's attention to the practice of small-scale aquaculture and provides a guide on how to responsibly use the water ecosystem and the steps needed to develop, test and market fish vaccines. The chapters will serve as introductions to these fields and up-to-date reviews of recent research advances. This book is intended for a wide range of readers, including nutritionists, disease specialists, feed formulators, students, extension specialists, and farmers, as well as university teachers, graduates and doctoral students in zoology, physiology, aquaculture, and biology in general.