Glad to help.
There actually is a Convict-like species called the Honduran Red Spot that's somewhat less aggressive. While I wouldn't trust it with Firemouths (I'd recommend keeping
Thorichthys spp generally away from other cichlids unless you are sure they'll be safe) it seems to work a bit more reliably in mixed species set-ups than Convicts. On the downside, with hybridisation being so common among careless aquarists, you can't always be sure the Honduran Red Spots really are pure-bred
Amatitlania siquia.
Now, the Firemouth, Peacock and Livingstoni combination might be okay. None of these is especially aggressive, and they each occupy somewhat different niches, so should ignore each other. Jaguars vary; my male specimen was a total pussycat most of the time and only really tangled with the Midas cichlid. But you do hear stories of Jags that are real terrors, and by any standards they're big, strong fish. So keep a close eye on it. The same for the JD; they're usually not too aggressive outside of breeding, but they are strongly territorial, so again, look out for signs of friction.
Most cichlids adopt an "out of sight, out of mind" attitude because they're strongly visual fish. Breaking up lines of sight will help a lot. Orient caves so they point towards the outside of the tank rather than the centre where the fish congregate. Place tall structures on the bottom of the tank that act as visual blocks, for example upright slates or bogwood roots. If you can get plants (perhaps plastic plants) that the fish won't wreck, they're great for this purpose.
Alternatively, "overstocking" can work. This doesn't really mean adding twice as many fish as your tank can hold, but rather, adding more fish that there are possible territories. Under aquarium conditions medium-sized cichlids typically claim an area around 50-60 cm across, if not larger. If you hold more (usually male) specimens of a given species in a tank than there are territories, those males can't establish territories, and territorial aggression is much higher when a fish has claimed a territory than when it is trying to find one. Seems paradoxical, but there you go. So if you had, say, a 55 gallon tank and placed 6 male Firemouths in there, it's unlikely any one male would be able to claim a viable territory, so aggression between them would be less. If you watch cichlids in retailer's tanks, you'll see this sort of thing: lots of threats, but rarely any actual fighting until the retailer is down to last couple of Convicts or whatever in the tank.
Personally, I'm not a fan of overstocking outside of Mbuna systems. Partly it's because you're locked into keeping lots of one cichlid species, so if you want "one of everything" this approach doesn't really work. But also because heavily stocked systems are harder to keep, and cichlids notoriously sensitive to nitrate, the scourge of heavily-stocked tanks. There's also the problem that when the fish get older and one or two of them die, then the remaining fish may be able to claim territories and before you know it they start seriously fighting.
Long term your Jaguar will need a bigger tank than 55 gallons anyway, so as/when he starts throwing his weight around you will want to rehome him. The JD is the wildcard, but with luck it's a female and won't cause too many problems, especially if the tank is well-stocked with rocks and plants, and perhaps even some very robust dither fish (Mexican tetras for example). Without the JD, you should find lesser mortals like Swordtails or the larger Rainbowfish do okay (providing of course they're too big for the Livingstoni to view as food!).
Thorichthys especially are rather shy, and if you have a group of dither fish with them they spend a lot more time in the open.
Cheers, Neale
Neale, Thanks a lot for the prompt response. I managed to return the convicts earlier today and exchanged them for a jaguar cichlid, I also added a lot of additional caves. Fortunately, the firemouth remains in one piece and had not encountered any major incidents with the convicts. Believe me, I had sort information online, but had been assured by another that breeding convicts would have been alright provided I had enough hiding spaces. I now comprehend that this cannot be the case as I have learned first hand.
The only pending potential problem is that I have mixed cichlids (african and new american) Dempsey, Firemouth, Jag, Peacock, and a Livingston all in a 55 gallon. Now that the convicts have been removed, they all appear to be cooperating a lot better, however, I know in time this will change. Other than hiding spaces, are there any better ways to further prevent tension in a cichlid tank?
