The black ruby barb (Pethia nigrofasciata) or purplehead barb is a tropical cyprinid fish endemic to Sri Lanka where it occurs in forested streams from the Kelani basin to the Nilwala basin, they are found in streams on hills around 1000 ft (300 m) in elevation. The brightly colored population introduced to Mahaweli at Ginigathena, Sri Lanka are said to have diminished in number due to the aquarium export trade.