The Nile crocodile (Crocodylus niloticus) is an African crocodile , the largest freshwater predator in Africa , and may be considered the second largest extant reptile in the world, after the saltwater crocodile (Crocodylus porosus). The Nile crocodile is quite widespread throughout Sub-Saharan Africa, occurring mostly in the central, eastern, and southern regions of the continent and lives in different types of aquatic environments such as lakes, rivers and marshlands. Although capable of living in saline environments, this species is rarely found in saltwater, but occasionally inhabits deltas and brackish lakes. The range of this species once stretched northward throughout the Nile, as far north as the Nile delta. On average, the adult male Nile crocodile is between 3. 5 and 5 m (11 ft 6 in and 16 ft 5 in) in length and weighs 225 to 750 kg (500 to 1,650 lb). However, specimens exceeding 6 m (20 ft) in length and weighing up to 1,100 kg (2,400 lb) have been recorded. Sexual dimorphism is prevalent, and females are usually about 30% smaller than males. They have thick scaly skin that is heavily armored.
Evidence exists of Nile crocodiles from cooler climates, like the southern tip of Africa, being smaller, and may reach maximum lengths of only 4 m (13 ft 1 in). A smaller population from Mali , the Sahara Desert and elsewhere in West Africa reaches only 2 to 3 m (6 ft 7 in to 9 ft 10 in) in length,  but it is now largely recognized as a separate species, the West African crocodile .