Formerly found in lakes and rivers throughout Africa, they are now more restricted, ranging from the upper Nile to South Africa. The pygmy hippopotamus lives alone or in pairs in the streams, wet forests, and swamps of West Africa.

A single young is born after gestation of about 8 months; the baby often rides the mother’s back while she swims or floats at the surface. In the breeding season, males engage in battles that are sometimes fatal.

Hippopotamus live in herds in rivers and swamps and feed, mostly at night, on water plants and shore vegetation, often doing much damage to crops. In water, from which they never wander far, they can swim fast and also walk along the bottom. On land they can gallop for short distances faster than a man can run.

Hippopotamus have barrel-shaped bodies and short limbs. They may reach a length of 4.6 metres (15 feet), a height of 1.5 metres (5 feet) at the shoulder, and a weight of 3 - 4.5 metric tons (3.3 – 5 tons). The skin is thick, nearly hairless, and grayish-black above, lighter and pinkish below. The eyes and nostrils protrude and may be kept above water when the animals are submerged. The mouth is enormous and the upper lip is thick and bulging; the incisor and canine teeth are very large and grow continuously as they are worn away. Numerous skin glands release a protective, oily, pinkish secretion that has popularly, but incorrectly, been thought of as blood sweated by animals. The rare pygmy hippopotamus (Choeropsis liberiensis) is about 1.5 metres long and darker in colour. It appears to be less aquatic than its larger relative.