Ecology and Conservation of Freshwater Fishes Biodiversity - Hardcoverby Rafael Miranda (Editor) Freshwater fishes are the most diverse vertebrate group, with almost 36,000 species described so far, and more species are being discovered all the time, evenly distributed between marine and freshwater habitats. Freshwater ecosystems serve as a habitat for more than 18,000 fish species, occupying less than 1% of the Earth's surface. Among all ecosystems, inland waters are one of the most affected. Wetlands are disappearing