Maybe you could convince the Hell's Angels to make some new friends? In all seriousness, Midus Cichlids are very aggressive and territorial. They can kill fish twice their size. They can also get huge. Tank mates are not a very good idea. A VERY large pleco may live because they stay out of the way but its iffy. Personally I'd keep the pair alone. Also, if you have 1:1, watch the female as cichlids have a tendacy to overmale solitary females and kill them if she isnt quite in the mood. Hope this helps.