This book is written in textbook format and presents an overview of different aspects of fish genetics in an understandable and systematic style. The materials of the book are divided into seven chapters. The first chapter reviews data on variability and evolution of fish chromosomes, meiosis and development of eggs and spermatozoa, and fertilization. The second chapter covers materials on Mendelian genetics in fish and includes data on inheritance of color, fin length and scale cover types. The third and fourth chapters review inheritance and analysis of quantitative traits, and DNA markers and their application. Materials on selective breeding, intraspecies and interspecies hybridization, inbreeding and methods of its reduction are presented in the fifth chapter. The sixth and seventh chapters review obtaining gynogenetic, polyploid and monosex progenies, production of transgenic fish, and genomics. The book is extensively illustrated and contains more than 80 figures and 16 tables. This book is intended for students and everyone who is involved in aquaculture and fisheries. Also, it could be interesting and beneficial for koi and aquarium fish hobbyists.