The cotton pygmy goose (Nettapus coromandelianus) is a small duck species that breeds in Sri Lanka. The male has a white head and neck, dark glossy green upperparts, and a dark brown breast band. Females are primarily brown and white, with a distinctive dark stripe through the eye. This species inhabits well-vegetated lakes, lagoons, swamps, and reservoirs, nesting and roosting in hollow trees near these water bodies. During the breeding season, females can lay up to 18 eggs, and the goslings stay with their mother until they are around six months of age.