So what exactly does the title of this post mean? If you’ve done your due diligence with regard to cichlids, then you’ve undoubtedly read they are naturally aggressive and more so than many other tropical fish in the hobby. However, your experience may not reflect that. Why? The variables.
Members of each cichlid species carry innate behaviors, but like humans, every cichlid has a personality. Yes, mbuna species are known to be pretty aggressive in aquaria, but the breadth and depth of that aggression depends on many things. The species, gender mix, aquascape, tank size, tank mates, water temperature, time of day, and amount of light are all variables that can determine how a specific cichlid behaves, including how aggressive it might be.
That cichlid your friend has that is a nightmare might be a whole lot friendlier under different circumstances. The challenge for you as a cichlid keeper is to be able to identify those circumstances and understand them. How do you do that? Just pay attention.