Why does everyone say not to mix africans and american cichlids? I had two oscars and 3 "mixed africans" my wife liked and brought home one day. They were fine together for about 3 years. The Africans didn't survive the move. Too stressed. There were all in a ninety by the way. I know everyone said not to mix, but I figured they weren't that expensive if the oscars didn't like sharing. Thanks