In the ever-evolving field of aquaculture, understanding the intricate nutritional needs of fish is paramount to ensuring their health, growth, and overall productivity. This new volume delves into the essential aspects of fish nutrition, focusing specifically on the crucial roles of proteins and amino acids in the diets of various fish species. A culmination of extensive research and expertise from leading experts in the field of aquaculture nutrition, the book covers fish digestion and protein utilization, proteins in fish feed and protein requirements of different species of cultured fish. It also addresses the amino acid requirements of fish, including their dietary needs for lysine, methionine, valine, tryptophan, phenylalanine, histidine, leucine, and arginine. Through detailed analyses and critical insights, this book explores the latest advancements in fish nutrition, highlighting key findings and recommendations for formulating balanced and nutritious diets. It serves as an invaluable resource for researchers, academics, and industry professionals seeking to enhance their understanding of fish nutrition and improve aquaculture practices.