Cauvery forms the western border of Melagiris, flowing from Mekedaatu till Hogenekkal, along the reserve forests of Kesthur, Bilikal, Mallahalli, Urigam, Natrampalayam and Odapatti of the Hosur Forest Division. These are the last forested tracts of the river before it enters the thickly populated low-lying plains. This stretch of the forest shelters many red-listed species like the Giant Grizzled Squirrel, Smooth Coated Otter, Lesser Fish Eagle, Mugger and Four-Horned Antelope, in addition to a rich and diverse flora on its banks. Tigers and Ratel have been recorded from the Karnataka bank, along with hundreds of elephants of the Nilgiri Reserve.
Aquatic communities and more specifically fish communities are very good indicators of the structure, function and disturbances of the ecosystem. But very little is known about the fish diversity of Cauvery in the Melagiris. No scientific research focusing exclusively on this aquatic ecosystem has been conducted in the near past. Also, freshwater fishes have unfortunately been out of sight of policy makers and general public in India. This is in spite of the fact that the country harbours the greatest number of endemic freshwater fishes in continental Asia, many of which are threatened and some probably extinct.
Freshwater fishes are increasingly threatened by a range of factors, including habitat loss, overexploitation and biological invasions. These are mostly a result of catchment fragmentation, dam/weir construction, water and aggregate abstraction, and the prevalence of illegal and highly destructive fishing methods such as small mesh nets, plant-derived toxins, electricity and dynamite.
KANS has come to the concluding stages of a two year long effort to document the fish diversity in the Cauvery river that flows along Melagiris and the habitat structure. 48 species of fishes were recorded of which 1 species is documented by IUCN as critically endagered, 3 as endangered, 3 as near threatened, 3 as vulnerable and 37 as least concern.