The book is a comprehensive and updated textbook that focuses on modern advancements in shellfish aquaculture and breeding technologies. Shellfish play a crucial role in global food security, coastal livelihoods, and sustainable aquaculture systems, and this book highlights their growing importance in response to increasing demand for high-quality protein and declining wild fisheries.The book provides an in-depth understanding of both classical and advanced breeding techniques used in commercially important shellfish such as shrimp, crab, oyster, mussel, clam, and scallop. It integrates traditional concepts with modern innovations including selective breeding, hybridization, genetic improvement, broodstock management, hatchery technology, and disease-resistant strain development.Special attention is given to practical aspects like larval rearing, seed production, and hatchery operations, along with emerging technologies such as genomic selection, cryopreservation, molecular tools, and climate-resilient breeding strategies. Designed for students, researchers, and professionals, this book serves as a valuable resource in fisheries and aquaculture science.