The Indus river dolphin (Platanista gangetica minor) is a subspecies of freshwater river dolphin found in the Indus river (and its Beas and Sutlej tributaries) of India and Pakistan. This dolphin was the first discovered side-swimming cetacean. It is patchily distributed in five small, sub-populations that are separated by irrigation barrages. The Indus dolphin does not form easily defined groups who interact. Instead, they're typically found in loose aggregations. From the 1970s until 1998, the Ganges River dolphin and the Indus dolphin were regarded as separate species; however, in 1998, their classification was changed from two separate species to subspecies of a single species (see taxonomy below).