The river flows to the north-west through a deep, narrow valley that widens and flattens into a broad floodplain below Clanwilliam.

The upper Olifants River is one of the main dwelling places of adult sawfins (Pseudobarbus serra).

At present it is so rare as to be jeopardized by angling or fishing and may not be killed or caught; a long-lived and slow-growing species, it needs several years to grow undisturbed but reaches an adult almost 40 cm after a decade.

Although in South Africa this relatively delicate fish is only Near Threatened, in Australia species of the same genus were driven to extinction by competing salmonids.

[8] Other species that occur in the Olifants riverine system include Twee River redfin, (Pseudobarbus erubescens), Fiery redfin (Pseudobarbus phlegethon), Austroglanis barnardi, Clanwilliam rock-catfish (Austroglanis gilli), Chubbyhead barb (Enteromius anoplus), and Clanwilliam sandfish (Labeo seeberi).

Non-biological threats are mainly excessive removal of river water for irrigation, and the resultant toxic surface runoff from plantations (especially agrumes).