The book, we discuss about the elements in fish endocrinology. Fish endocrinology is a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions called hormones, as well as the integration of developmental events proliferation, growth, and differentiation. The chapters in the book have been contributed by eminent scientists/academicians active in the areas of fish endocrinology. The book will not only meet the requirement of students but will also be useful as a guideline to the teachers and researchers.