https://phys.org/news/2018-07-scientific-earth-iconic-freshwater-fish.html

Of the 18 currently valid species of mahseer, the official IUCN Red List of Threatened Species currently lists four as endangered, one as vulnerable, and one as near threatened. The rest either lack enough data to reach a conclusion or haven't been evaluated.

Recent research published by colleagues and I in PLOS ONE focused on the hump-backed mahseer, the largest and most endangered of all mahseers. The fish was once common throughout the Cauvery river and its various tributaries in southern India, but it is now limited to just a handful of small isolated populations. Weighing as much as a small adult human (55kg), this freshwater giant qualifies as megafauna, yet bizarrely it has remained a taxonomic enigma without a valid scientific name.