I have mixed central american and even south american cichlids with africans several times with great success. Water parameters and diet werent so much a problem as was the aggression of the fish in relation to their size. I had an Acei and a Flowerhorn in with south americans and they did fine. They fought a bit with eachother but none suffered from water parameters. My fish usually come from larger retail chains who have centralized systems meaning every tank has the same water. They do fine there and they usually do fine with me.