Is it possible to have Blood parrot fish and really aggressive fish in the same tank?
I guess you could, but I think it looks a bit stupid, putting a fence in the midlde of your tank. In that size tank the Oscar and blood parrots may get on perfectly OK, especially if you start out with large parrots and a small Oscar. Oscar are greedy eaters, but not super aggressive. If there is enough room in the tank it will probably leave the parrots alone. Red devil, probably kill ANY tankmates, including an Oscar. It does depend on the temperment of the individual fish of course, so have a plan B ready in case it doesn’t work out.