I never had Malawi cichlids before but I've read on numerous occasions that you can remedy bullying by rearranging your ornaments and/or rocks so that it can break up established territories and create breaks in the line of sight. Or if your tank is quite barren, and if you have the room, try adding in some more decor (i.e. Rocks, caves, plants, etc.) to give them peace from one another. Some have even gone as far as to take the bully out and put him in a bucket for a "time-out" session. As strange as that sounds, they claimed it worked... LOL