I have 3 rb parrots ranging from 4-8" in a 450ltr with raspboras & glowlight tetra. The other fish were in the tank a good while before I introduced the rb parrots. I've had no issues with them, they all do there on thing & ignore everyone else lol. Even at feeding time they just seem to gentle nudge each other if they're after the same piece of food.
I know they are a controversial subject but I am glad I bought them, they are so curious and once over their initial shyness, very interactive.