Mahseer is the common name used for the genera Tor, Neolissochilus, Naziritor and Parator in the family Cyprinidae (carps). The name is, however, more often restricted to members of the genus Tor. The range of these fish is from Vietnam in the east and China in the north, through Laos, Cambodia, Thailand, Malaysia, Brunei and Indonesia, and across southern Asia including the countries of India, Nepal, Bhutan and Bangladesh within the Indian Peninsula, plus Sri Lanka, Pakistan and Afghanistan. They are commercially important game fish, as well as highly esteemed food fish. Mahseer fetch high market price, and are potential candidate species for aquaculture. Several of the larger species have suffered severe declines, and are now considered threatened due to pollution, habitat loss, overfishing and increasing concern about the impacts of unregulated release of artificially bred stock of a very limited number of species.

Neolissochilus is a genus of fish in the family Cyprinidae native to freshwater habitats in Asia that are often grouped with the mahseers. The largest reach up to 1.2 m (3.9 ft) in length, but most species are much smaller.