Le Clos earned two medals on day one, shining in his specialist stroke as he secured gold in the 200m butterfly and bronze in the 50m sprint.
He was exactly one second clear of Australian Grant Irvine in the 200m event, touching the wall in 1:54.32, and settled for third position in the 50m race in 23.76 seconds, edging countryman Ryan Coetzee for the last podium place.
Le Clos struggled, however, in the 200m individual medley, trailing home in eighth position, more than five seconds behind World Championships silver medallist Kosuke Hagino of Japan.
Prinsloo snatched bronze in the women’s 200m backstroke in 2:10.04, with Australian Belinda Hocking coasting to victory in 2:06.66.
Prinsloo also took fifth place in the women’s 100m freestyle, and Le Clos’ training partner, Myles Brown, was fifth in the men’s 400m freestyle.