The aim of this book is to provide reader the use of zooplankton as bioindicator and a tool for water resource management. It contains four chapters. Chapter 1 clarifies the importance of zooplankton. Chapter 2 is about methods of zooplankton collection, preservation and analysis of zooplankton samples. Chapter 3 discusses about the advantage of using zooplankton as bioindicators and states of bioindicators on ecological, environmental and biodiversity states. Use of zooplankton for water resource management is discussed in Chapter 4.