Abstract: Aquatic ecosystems are the main source of biodiversity. These are an essential reservoir and a source of many biological products. Both aquatic ecosystems and the biodiversity are interrelated to each other and they perform major functions and are valuable and essential for the sustainability of biotic communities. Aquatic biodiversity in both freshwater and marine water are under continuous decline because of over exploitation of species, pollution sources from cities, industries and agricultural zones, loss and changes in ecological niche. Their conservation and management is essential for the protection of the aquatic biodiversity. This review is presenting information on biodiversity in aquatic habitats and their resource in marine and freshwater ecosystems and restoration mechanism.