If it was me, I wouldn't put any of those fish in a 30G, even alone. Those fish get huge. I would maybe put a pair of those fish in a 30G for breeding purposes, but they would be in there 1-3weeks tops.
Do you have any idea how big severums get- they are some of the biggest cichilds out there. Just one needs AT LEAST a 75 gallon tank. Why don't you google a few of the fish you have and see what it says? The only cichlids you can put in a tank that small are dwarf cichlids.