Die Kleinbek-geelvis (Labeobarbus aeneus) is ‘n varswatervis wat natuurlik voorkom in die Oranje- en Vaalrivier-stelsels in Suid-Afrika. In Engels staan die vis bekend as die Smallmouth yellowfish. Daar is twee pare baarde om die mond. Die vis is silwerkleurig met swart vlekke op wanneer dit onvolswasse is en die volwasse vis is goud-olyfbrons aan die bokant en roomkleurig aan die onderkant. Die anale vin het ‘n oranje skakering. Die vis word tot 50 cm lank en die Suid-Afrikaanse hengelrekord is 7.837 kg.
The smallmouth yellowfish (Labeobarbus aeneus) is a species of ray-finned fish in the genus Labeobarbus. It has become an invasive species in rivers of the Eastern Cape, South Africa, such as the Mbhashe River. The Orange–Vaal River system is one of the few in South Africa that is truly international. The source of the Orange river is in Lesotho and that of the Vaal on the Mpumalanga highveld whereas their tributaries extend well into most provinces of South Africa as well as into Botswana and Namibia. The Orange river eventually flows into the Atlantic Ocean at Oranjemund on the West coast border between South Africa and Namibia. The river drains hugely diverse terrestrial habitat types ranging from grasslands, mountains and karoo to desert. This results in diverse riverine habitats that include clear mountain streams, turbid waters of the middle Orange river and the nutrient-rich discoloured water of the lower reaches of both rivers. Several in stream dams have changed the natural flow of the upper reaches to a regulated flow in the middle and lower reaches. This river system is home to South Africa’s best known and favourite sport yellowfish, the Orange-Vaal smallmouth yellowfish, L. aeneus.