The book introduces fish distant hybridization, which covers the basic theory and applications of fish distant hybridization as well as the main biological characteristics of different ploidy fish at the individual, tissue, cell, and molecular level. It is divided into 12 Chapters. The research progresses of animal distant hybridization and polyploids in domestic and overseas are summarized in this book. The characteristics of these hybrids and polyploid fish are also illustrated on basis of considering factors of the chromosomes numbers, phylogenetic relationship, reproduction, appearance, feeding habits, growth rate, and stress resistance. The creation of fish distant hybridization lineages will provide a clear genetic background which is helpful for the study of the strain generation as a model in genetic variation characteristics and reproductive characteristics. Fully illustrated in color, this book provides unique ideas in system description and presentation of distant hybridization and polyploidy fish. In fish genetic breeding, the tetraploid fish lineage and diploid fish lineage, formed through distant hybridization, can be used for preparing large-scale triploid and diploid fish. This book is a useful reference for researchers in fish genetic breeding, aquaculture, developmental biology, and animal evolution, and serves as a valuable resource for students and researchers engaging in zoology, evolutionary biology, and genetics.