Don't forget the bichir.Yeah I don’t think it will work. The Oscar will need a 125g tank with maybe another Oscar. If your going to do that get the other Oscar now so they grow together. Better chance of them getting along if they grow together. As for the flower horn it will need to be alone. Even another flowerhorn won’t work. There’s people here who keep just one in 250g tanks. They’re big and aggressive.
What kind of bass do you have?