This book ((Fungi in Aquatic Environment:Occurrence, Physiology, Biodegradation)) as a review for fungi activity in aquatic environment it give a knowledge for fungi occurancy in different water habitats (fresh and salinity water) like: streams, shallow lakes and wetlands, deep lakes and reservoirs and Hypersaline habitate. also the book focus on the impact of Temperature and climate change on living of Aquatic Fungi. which fungi enzymes have a big role in bio-degradation and recycling materials in aquatic environment therefor this book include enzymatic activity like: Lignocellulosic materials, extracellular ligninases and other enzymes: Phenol oxidases, Heme Peroxidases, Manganese peroxidases and Versatile peroxidases and their activities in biodegradation.