As the physical properties of water and air strickly dissimilar and consequently, the aquatic realm is to different from our terrestrial one for there to be relationships between them. The aquatic environment may impose strict requirements or offer unique challenges which have resulted in some most novel functions in fishes having no counterpart in terrestrial animals. For examples, some fish can detect low-level electrical field, and cave fish can live well without vision. Although in principle the options of endothermy and ectothermy are available to fish, most fish are in fact ectothermic. What are the trade-offs? In this class, I’ll select the areas of greatest general interest. We’ll have chapters on topics such as feeding and Disgestion, Swimming, Growth and Metabolism. Stress and Immune Response, Ecothermy, Osmoregulation, Biorhythm.