Amazon River

The Amazon River Basin is a propitious habitat for various species of fish, making it the leader of freshwater fish species worldwide.

An excerpt from the article 20 facts about Amazon River

There are over 3,000 species of fish, including the Red-bellied piranha, the Tucunaré Peacock bass, the Arapaima, the Armored catfish, and the Bull shark. 

Up to 60 species of piranha live in Amazonian waters, as well as over 100 electric fish species, including the famous electric eel.