Various antelope species such as greater kudu and lesser kudu, eland, impalas, roan and sable antelope, grant’s gazelle and the tiny dikdik thrive in the grasslands bordering the river alongside giraffe, zebra, warthog, mongoose, porcupine, wild cat and civet. In the plains, ostriches, cheetahs and lions can be seen.

One of the very special attractions of Ruaha National Park is to be able to see both greater and lesser kudu and roan and sable antelope in the same Park.

Ruaha National Park is dominated by large populations of predators like the lion, leopard, and cheetah as well smaller predators like the hyena, jackal and wild dog. Tanzania is a critical country for wild dog conservation as it holds the largest population of wild dogs in the world including the second largest population in Ruaha National Park, after Selous Game Reserve.

Ruaha National Park also possesses the world’s largest elephant sanctuary. Groups of elephants frequent many areas of the Park.

Crocodiles and Hippos are numerous in the Great Ruaha River.

Bird life is prolific. Over 370 species have been recorded in the Ruaha National Park some of which are not found in Northern Tanzania. Eurasian migrants flock to Ruaha National Park twice a year – March to April and October to November - joining the resident kingfishers, hornbills, sunbirds, egrets, plovers and fish eagles.

The best time for keen bird watchers to visit Ruaha National Park is between January to April.

The Usangu flats 50km southwest of Ruaha National Park provide the source of the Great Ruaha River. The Mzombe River forms the Ruaha National Park's northern boundary and also flows into Mtera dam. Mtera and Kidatu dams were created to provide electricity for Dar es Salaam and most of Tanzania. Below Kidatu, the Great Ruaha then joins the Rufiji River and flows through the Selous Game Reserve and into the Indian Ocean.

In recent years the Great Ruaha River has stopped flowing towards the end of the dry season and is reduced to pools which teem with fish, Crocodiles and Hippos.

There are about 38 species of fish which have been identified in the Great Ruaha River. They traditionally provide an important part of the diet of people living along the river.

Within Ruaha National Park crocodiles have apparently increased in recent years and now some very large ones can be seen along the riverbank. There are also many hippos that use the river by day and come out to graze at night on the surrounding grassland.