Mahale National Park contains at least world's largest protected population of the eastern subspecies of chimpazee. The area contins atleast 337 bird species, many of which are rare and endemic to the Albertine Rift. Eg Perl's fishing owl. One of the unusal things about mahale is the wide variety of habitat types that it contains. The park is a mosaic of overlapping rainforest, woodland, bamboo forest, montane forest and mountains grasslands, meaning that mahale can support a unique mix of flora and fauna that rely on the various different habitats.

Mahale contains eight primates in additional to chimps, these are yellow baboons, blue monkeys, red colobus, pied colobus, and vervet monkeys two or three species of Galago. Lake Tanganyika which is part of mahale, is both the world second longest and second deepest freshwater lake being 673 in length and 60-80km in width. The lake is home to at least 400 species of fish, about 250 of which are cichlids, and 98% of which are endemic (occurs nowhere else on earth).