The black caiman (Melanosuchus niger) is a large crocodilian and the biggest extant member of the family, Alligatoridae. It is a carnivorous reptile that lives along slow-moving rivers, lakes, seasonally flooded savannas of the Amazon basin, and in other freshwater habitats of South America. It is a quite large species, growing to sizes of at least 5 m (16 ft) and possibly up to 6 m (20 ft) in length. The black caiman is the largest predator in the Amazon ecosystem, preying on a variety of fish, reptiles, birds and mammals. They are generalists and an apex predator, potentially capable of taking any animal within its range, including other predators. Few ecological studies have been carried out on the species but it can be noted that the black caiman has its own ecological niche that enables coexistence without too much competition.

(source: wikipedia)