In my opinion this was over crowded to start. Cichla are messy messy fish and require a very large amount of filtration, that of which I can't imagine you have in a 20 gal. These kind of questions however are all based on opinions, and there's no real fact.
Know this though, that there are members who have put a few of these guys, smaller than yours, in a 20 gal and had very unsuccessful turn outs, but there are also some who have flourished personally, when I bought 2 baby bass, about 1 inch, they went in a 55 by themselves.