Eel of the genus Anguilla is an extraordinary fish, which due to its particular life cycle has fascinated biologists and physiologists ever since the pioneering works of Homer H. Schmidt in the 1930s. The Eel has become an excellent model for various aspects of adaptive physiological research. Despite that, several books dealing with eel biology, aquaculture, fishing, etc., have been published, but there still is a need for a text dealing with eel physiology. This book fills a void in eel literature by presenting various aspects of eel physiology in one comprehensive volume. With its numerous figures and tables and an extensive up-to-date bibliography, it will be of interest not only to researchers and students but also to people engaged in applied research in fishery and aquaculture. Eel is a commercially important fish, but it must be protected from over-exploitation; as such, conservation measures are necessary. It is hoped that this book will stimulate and suggest new lines of research.