The Grass Carp is a large freshwater fish introduced to Sri Lanka for aquaculture and the biological control of aquatic weeds. Native to eastern Asia, it is now found in reservoirs, lakes, irrigation tanks, canals, and slow-moving rivers throughout the island. It prefers warm freshwater habitats with abundant aquatic vegetation and open swimming areas. As its name suggests, the Grass Carp is primarily herbivorous, feeding on a wide variety of aquatic plants, grasses, algae, and other vegetation. It is an active, fast-growing fish that spends much of its time grazing on submerged and floating plants. Juveniles may also consume small aquatic invertebrates, but adults rely mainly on plant material. In Sri Lanka, the Grass Carp is widely used to help control excessive aquatic weed growth in reservoirs and irrigation systems while also serving as a valuable food fish. However, as an introduced species, large populations can significantly reduce aquatic vegetation, potentially altering natural habitats and affecting native freshwater fish and other aquatic organisms.