This comprehensive, introductory-level reference work aims to unite readers in the wonders of fish physiology. Chapters highlight where physiological systems and processes are conserved across vertebrate groups, which supports the use of fish as a vertebrate model for investigating fundamental problems in physiology and knowledge transfer to the medical field. The new edition greatly expands the closing thematic section focused on applying fish physiology to real world challenges with topics including ocean acidification, declining habitat quality due to human activities, and the use of zebrafish in biomedical studies on tissue regeneration, neurological disorders and cancer.