This well-marked genus, containing four species—one African, one Indian, and two Australian—is distinguished by its small size and short goose-like beak. The bill is very high at the base and narrows gradually in front; the nostrils are small, near the base, and oval; wings pointed; tail short, rounded, of 12 feathers. Feet placed far back ; hind toe with a narrow, but distinct lobe. The sexes differ but little in winter, but in the breeding-season the male assumes a somewhat brighter and more distinctive garb.
Although the bill is shaped somewhat like that of a goose," Cotton Teal," as they are called in India, differ widely from geese in structure and habits. Geese feed almost entirely on land, walk well, are rarely seen swimming, and seldom dive, whilst members of the genus Nettopus are very poor walkers (though by no means, as stated by some writers, unable to walk) and are always found on the water, whether feeding, resting, or sleeping, except when they perch on trees, and they dive freely. Neither in flight, voice, structure of the trachea, nidification, nor plumage is there any resemblance between Anser and Nettopus.