This book is based on the research work carried out as a part of Erasmus Mundus Master of Science in Marine Biodiversity and Conservation at Oviedo University, Spain. The major allergens in fish are the parvalbumins, Ca-binding proteins involved in muscle contraction and other functions. This book provides comprehensive information on characterization of parvalbumin genes in representative species of Salmonidae, in order to understand their molecular relationships and to assess their potential significance for allergy associated risk in humans. Designing of Primers, DNA extraction, PCR amplification of Ca-binding sites, cloning, sequencing, reconstruction of phylogeny, inferring putative protein structure employing state-of-the art methodology are included in this book. I strongly believe this book will be very much useful for the students, researchers and Professors working with Molecular Biology and Genetics in all parts of the world.