A yellow/greenish fish with a pronounced overbite that can grow to about 60cm, the Clanwilliam sandfish is one of South Africa's most threatened migratory freshwater fish.

Having disappeared from the Olifants River where it was formerly abundant, it survives only in the Doring River and some of its tributaries.

Here it battles black bass and bluegill – fish introduced from the US in the late 1920s for sport fishing. And it's a battle the sandfish appears to be losing.