One African lake grew more fish species than the whole Atlantic Ocean
Lake Malawi is home to an estimated 700-1,000 species of cichlid fish, nearly all found nowhere else on Earth, having evolved from a common ancestor in a geological blink of an eye. Their explosive diversity in color, diet, and jaw shape makes the lake one of the fastest-known cases of species formation in vertebrate history.
— Wikipedia contributors, Lake Malawi — Great Rift Valley, East Africa