Chapter 1. Freshwater microbiology: recent updates and prospects -- Chapter 2. The Chemical Composition of the Water in the Rivers, Lakes, and Wetlands of Uttarakhand -- Chapter 3. Microbial diversity of cold-water reservoirs and their prospective applications -- Chapter 4. Overview of microbial associations and their role under aquatic ecosystems -- Chapter 5. Plant-microbe interaction in Freshwater ecosystem for improving water quality -- Chapter 6. Microbial interactions with aquatic plants -- Chapter 7. Status of Microplastic pollution in the freshwater ecosystems -- Chapter 8. Heavy metal pollution in water: Cause and remediation strategies -- Chapter 9. Recent advances in biological wastewater treatment -- Chapter 10. Recent developments in wastewater treatments -- Chapter 11. Wastewater treatment: perspective and advancements -- Chapter 12. Overview of methods and processes used in waste water treatment -- Chapter 13. Role of microorganisms in polluted water treatment -- Chapter 14. Bioremediation of Polluted water -- Chapter 15. Pollution in freshwater: Impact and Prevention -- Chapter 16. Fresh water pollution: overview, prevention and control -- Chapter 17. Iron Degrading Bacteria in the Aquatic Environment: Current Trends and Future Directions -- Chapter 18. Bioactive compounds from aquatic ecosystem -- Chapter 19. Freshwater BGA: A potential candidate for sustainable agriculture and environment for the welfare of future planet earth -- Chapter 20. Factors affecting Fish migration.