What to add to cichlid tank?

Dempsey's are hard to put other fish with...from personal experience i never was able to house them with other fish that's one of the reasons i don't keep them anymore....if you wanted to try i would say maybe there are 2-3 fish that are just as "tough" as the Dempsey's. one being the Red Devil two being the Jaguar cichlid and three would be the Texas cichlid...the only problem with having these fish mixed together is that there all predatory fish and will constantly fight even the two Dempsey's if their both males they will fight when they hit maturity as well and it will be a disaster for you...they also have a problem with digging up plants and moving the gravel around and what their actually doing is marking the territory already so don't be surprised if they start to fight sooner than later...i hope this was a help to you and good luck!