hi,
I had 20 convicts, 2 green terrors, and 2 albino tiger oscars in a 4ft tank and the convicts kept bullying the oscars, and I had to seperat them (eventually they died).
The green terrors were ok, but were getting nipped at and seemed stressed.
Since I put the convicts and green terrors into a 230gal tank, the green terrors have grown nicely and arent being nipped at anymore. Since then Ive been able to add some lombardois, electric yellows and clown loaches and they are all getting along fine.
As long as you have plenty of room for territory especially when the convicts have babies you will be fine. The convicts will chase any fish away but will not pursue them - instead will return to look over the babies.
So just as stated before, make sure the oscar is the biggest, then the green terrors, and then the convicts - unless you have plenty of room.
Polak