They are usually not that aggressive. Mine never had any problems, but was alone in an mbuna tank (when I first started and didn't even know there were many different types of african cichlids). He did hold his own though against the mbuna. He wasn't the king of the tank, but didn't allow anyone to bully him.
Here is a link to look at if you want. You can also look into other profiles of other species and types of cichlids for information.