Good thing I read this i am getting rid of my tiger oscar and was about to get a FH fom a guy I know, I have a red oscar who is my fav fish and I dnt want him killed by the FH. I have a 55.
I think you should pass on the oscars and look into a bigger tank for the fish you have now. If you get a big enough tank you can fit more fish that you like. Oscars are messy eaters and poop a lot therefore you would need good filtration to back it all up. Your fish might seem fine right now but they all are going to grow big. Perhaps not the convicts but they can carry a punch in agressiveness. Just my two cents good luck though
Flowerhorn needs solo tank, aside from being aggressive, flowerhorns are territorial. I will kill even a female flowerhorn, unless its mating. Even in breeding flowerhorn, tank dividers are use for weeks just to introduce the male & female.