Solo or 3 is probably fine. Depends on the personality of the ones you get. Mine is pretty laid back except with the leporinus.
FINWIN
can give you stories about her’s. Solo gives you more options in terms of space for tankmates, but by their nature parrots are pretty incapable of causing real damage (unless you have a particularly functional or aggressive one... then they go full Midas).
This. I've got four parrots. The two females are the worst with aggression. One has a mouthful of teeth and the other a single fang up top (she likes to stab stuff like a spear). The laid back male can't do damage the same way, so he headbutts, body slams and rips lips...my 10" choc gets a busted lip once a week. My other male is a nervous screwball who jumps at shadows, ghosts and whatever. They're all between 7" to 8" and in separate tanks.
The nervous male (Tango) can't get along with other parrots. He gets aggressive. But he's hyper and jumpy around other types of fish though. Actually has some teeth but doesn't have enough aggression to use them.
The tactical male (Boss) picks and chooses his fights and has middle of the road aggression. He learns quickly how to fight different fish. Head butted my Oscar (Brick) once he got too big to lip lock with.
The female with the fang (Kong) is like an assassin, always in aggression mode with shark fins up. Can't be trusted with other fish. She has one mode, seek and destroy. She beat up both males.
The #1 kickass and take names Queen (Patch) with the mouthful of teeth has beaten up
every other parrot. How badass is this one? She sliced up Kong and put her in the corner. Kong had a crooked face for weeks.
I've got personality profiles on 'em in another thread.
You could get 2 in a 75 comfortably. Give everyone good size pots or caves and plants as they like 'hiding' and get away space at times. Dithers like mollies and swords wouldn't hurt.