Mahale is home to the world's largest protected colony of eastern Chimpanzees (about 700-1000).
At least 337 bird species have been recorded in the area, many of which are uncommon and peculiar to the Albertine Rift. Pel's fishing owl, for example.
The broad variety of habitat types found on Mahale is one of its most remarkable features. Mahale can host a unique combination of plants and species that rely on the many habitats because the park is a mosaic of overlapping rainforest, woodland, bamboo forest, Montane forest, and alpine meadows.
In addition to chimps, Mahale is home to 8 (possibly 9) primates, including yellow baboons, blue monkeys, red colobus, pied colobus, and vervet monkeys, as well as two or three Galago species.

Lake Tanganyika, part of Mahale, is the world's second longest and second deepest freshwater lake, with a length of 673 kilometers and a width of 60-80 kilometers.

Lake Tanganyika has one of the most diversified fresh water fish faunas on the planet. There are at least 400 fish species in the lake, with roughly 250 of them being cichlids and 98 percent of them being indigenous (the occur nowhere else on earth)