I had a very well established environment in my aquarium consisting of assorted tetras, barbs, and angelfish. Then earlier this week, without doing any research, I introduced two yellow lab cichlids in my aquarium. This afternoon when I got home from work, I found one of my very healthy angels laying dead on the bottom. Could this be the work of the Cichlids dhowing their aggressiveness? Should I remove the cichlids from my aquarium before any more of my fish mysteriously die?