Oh, this is much better than cichlid-forum for most stuff. I'm gonna say no, have not kept barbs or sharks, but i bet african are a bit more agrisive and fast then the sharks would like also the water requirments are different the cichlids should be in hard water with aph of at least 7.5
Sorry can't give you a definate answer I had seen this thread or maybe another one of yours but didn't post cause I've had no expirence with those fish but if your begging for a reply that's the best I can give. It's not that anyone is against noobs