i guess it depends on which kind of african cichlids i only know about the ones from lake malawi, they are beautiful and you have a colorful variety you won't need to mix them with other fish , but in answer to your question, they will kill any community fish you put with them if they can catch it..you can't mix them, but you can crowd your tank in fact it's best to so no one fish the dominant one can establish territory.i have 2 55 gallon tanks one is for mbuna cichlids such as red zebras, the other is a cichlid peacock tank. its not good to mix peacocks with other cichlids cause of agression. both my tanks have a synodontis catfish, siamese algae eaters and 12 cichlids in them , there is no fighting,and no algae ( and i have all live plants).
and lots of rock. they love rocks... hope this helps..