A huge tank is needed for those fish alone, oscars will and do reach a foot in length, plecos (depending on the species) can reach 2ft and also grow territorial towards each other as they grow,
This type of set-up needs nothing less that 150 gallons to thrive in the long term IMO, there are a lot of potentially huge, potentially fairly aggressive fish in there.
As for the convicts, your parent convicts are going to become very territorial, especially when the eggs hatch. If anything I'd be worried about how the rest of your fish are going to get on with two aggressive spawning fish. It is unfortunately likely, as unwritten said, that your other fish will get the eggs or fry, especially when free-swimming.