The Indus River dolphin (scientific name: Platanista minor) is freshwater cetacean closely related to the Ganges River dolphin (Platanista gangetica). These two endangered dolphins were long regarded as a single species and some regard them as two subspecies rather than distinct and separate species. Though Platanista minor and Platanista gangetica barely differ morphologically except for slight differences in tail lengths, the two species are distinguishable by their ranges. Platanista minor occurs only in the Indus River system, while Platanista gangetica inhabits only the Ganges River system.

The close connection of these species is likely explained by the fact that "until the late Pliocene, the present-day Indus, Ganges and Brahmaputra (except for the upper reach, the Yarlung Zangpo Jiang Rivers constituted a single westward-flowing river called the Indobrahm (Hora 1950, 1953). As Mohan and Dey note, even up until historical times there was probably sporadic faunal exchange between the Indus and Ganges drainages by way of head-stream capture on the low Indo-Gangetic plains, between the Sutlej (Indus) and Yamuna (Ganges) Rivers.