According to the Zootierliste, the following zoos in South Africa currently keep caimans.
National Zoological Gardens of South Africa
Brown Caiman (Caiman crocodilus fuscus)
Yacare Caiman (Caiman yacare)
Benoni Monkey And Bird Park
Spectacled Caiman (Caiman crocodilus)
Cuvier's Dwarf Caiman (Paleosuchus palpebrosus)
Hartebeespoort Dam Snake and Animal Park
Spectacled Caiman (Caiman crocodilus)
Emerald River Lodge - Animal World Game Park & Zoo
Cuvier's Dwarf Caiman (Paleosuchus palpebrosus)
Crocodile Centre St Lucia
Cuvier's Dwarf Caiman (Paleosuchus palpebrosus)
Incidentally, South Africa is one of the few countries in Africa that keeps not only caimans but also American Alligators (Alligator mississippiensis), which belong to the same Alligatoridae.