Salvini may be a little more reclusive than some of those others you've mentioned, but they are by no means "somewhat passive" fish. Quite the opposite, in fact.
But I'm having a huge debacle with mine at the moment, so don't assume that I have the answers either.
Now that my spawning pair is divorced, and the fry have all been eaten, I'm seriously considering doing a similar setup to what you're describing, sweetpickles. More of a mixed CA community of sorts.
Point being, I'd be very interested in figuring out what has a decent chance of working in a 55 gal. tank as far as this type of aggressive community goes. I've been working on figuring this out over at the cichlid-forum as well, and so I can give you a bit of advice right now...
First off, the JD is too big for a 55 gal. tank.
I'd go so far as saying that it'd be too much even alone, but perhaps that is up for debate. With other CA cichlids in a 55 gal. tank---not a chance, IMO.
That leaves you (out of the fish you mentioned) with salvini as the tank bosses. For this reason, you'll only be able to have one in this mix. Males hate each other, so keeping two would just end you up with a dead one and one survivor. Keeping a male and female would likely result in a spawning pair which---although perhaps not an absolute certainty---would result in a fairly distinct possibility of resulting in the death of the FM's and/or possibly some of the convicts.
Keep in mind I've never tried this.
All of this comes from my discussions on the topic with more experienced folks over on the cichlid-forum.
With a lone salvini, firemouth(s), and convict(s)...not even sure if you should have more than one of each of the FM & convict...perhaps even another species or two (not sure which other species would hold up in a mix like this), I think it has a good chance at working.
As for which ones and how many of each......that is something I'd like to find the answer to as well.
BV
