Hi Fishjones
SA Cichlids are terrific fish to keep!

I have a SA tank due to my low
pH level. What is your PH level? Most SA Cichlids prefer a lower PH.
Jack Dempseys are great fish, I have two that I really enjoy but they are pretty shy and tend to dart around the tank if I move suddenly. The convict would get along ok with them and IMO I would go with only one convict, as you will cut down on any aggression if you ended up with a mating pair of convicts. Are these fish for your 120g tank? You can add one oscar with them or some silver dollars and a SA catfish. Unfortunatly there are a lot of SA Cichlids you would not be able to add with the
JD like, angels, Discus, cardinal tetras. Any other SA cichlids you are thinking about adding?