They are among the smallest waterfowl in the world and are found in small to large waterbodies with good aquatic vegetation.

The cotton pygmy goose was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae.

[4] The cotton pygmy goose is now one of three species placed in the genus Nettapus that was introduced in 1836 by the German naturalist Johann Friedrich von Brandt.

[7] Members of the genus are sexually dimorphic, with the cotton pygmy goose the only species in which there is a marked difference in the non-breeding plumage of the males.

Males have a dark brown forehead and crown and a blackish green broad collar at the base of the neck.

The collar is replaced by spots and the face is flecked and neck finely vermiculated unlike the male.

Winter dispersal is also wide and individuals have been seen as far west as Arabia,[13] and Jordan[14] and they are regularly found on islands in the region such as the Maldives and the Andamans.

Stomach analysis showed that they fed on small fishes Puntius, Mystus, Oryzias, molluscs, crustaceans, insect larvae as well as plant matter from species such as Ipomoea, Hydrilla and Ruppia.

The males assist in locating nests but incubation is thought[19] to be by the female alone which lays 6 to 12 ivory-colored eggs per clutch.

Sir Harcourt Butler noted a nest at a height of 68 ft (21 m) under the eaves of the roof of the residence of the governor in Rangoon.

[27] Hume noted that the numbers of migratory ducks sold in the Calcutta markets declined over ten years but not those of the cotton teal.

[28] The Sinhala name of mal saar or flower teal is based on the colours and possibly the habitat of lily-covered ponds.

The name "cotton teal" was used by Europeans near Bombay who noted that the bird had a lot of white feathers.

Samuel Tickell recorded a Kol name from Singhbum of Merom-derebet, merom being a goat and the call likened to a bleat.