Hormones and Reproduction of Vertebrates, Volume 1: Fishes is the first of five second-edition volumes representing a comprehensive and integrated overview of hormones and reproduction in fishes, amphibians, reptiles, birds, and mammals. The book includes coverage of endocrinology, neuroendocrinology, physiology, behavior, and anatomy of fish reproduction. It provides a broad treatment of the roles of pituitary, thyroid, adrenal, and gonadal hormones in all aspects of reproduction, as well as descriptions of major life history events. New to this edition is a concluding assessment of the effect of environmental influences on fishes. Initial chapters in this book broadly examine sex determination, reproductive neuroendocrinology, stress, and hormonal regulation as they relate to testicular and ovarian development and function. Subsequent chapters examine hormones and reproduction of specific taxa, especially teleosts, with additional coverage of reproductive cycles of agnathan, chondrichthyan, and sarcopterygian fishes. The book concludes with an examination of the environmental influences on hormones and reproduction of fishes, including endocrine-disrupting chemicals, microplastic particles, and climate change.