I have a parrot a blue acara and an oscar in a 55 gallon tank. they are all three juveniles so they are fine in the tank. my question is what would be a suitable size tank for this trio?

i say think big.
By getting a bigger tank than stricktly nescesary, you will not need another upgrade.
Chances are you will want to upgrade when your fish start to grow.
A 75Gl could do, but i say 100+Gl

Watch out for the Blue Acara, they become more aggressive the older they get and whereas they probably won't have a pop at the Oscar, I'm almost certain they will go after the parrot. I don't think they will necessarily cause any injuries, but I think you may have a little bit of aggro unless you have got quite a big tank. As for tank size, I think you should be looking at at least 100 gallons.

what if I got rid of the blue acara and just kept the I and the parrot? would an 80gallon tank be sufficiant for these two?

that could work fine. the blue's are aggressive as OFL said.

Get the biggest tank you can afford or you may find in the future you want to upgrade again. It can get very addictive keeping fish

yeah I hear ya. I've been keeping for about five years now. I've kept almost all of the common aquarium store tropical fish I've found, except for new world cichlids. I currently am running a 55 gallon turtle and goldfish tank, a 10 gallon guppy breeder tank for feeding the oscar, and my 55 gallon a my cichlids. I am taking the blue acara back today in attempt to reduce aggression in the tank.

my parrot hides pretty constantly at the moment. will removing the acara make the parrot more inclined to swim freely or will he still be timid of the oscar?

if your serious about it, and really like keeping fish, get the biggest tank you can afford to buy, because eventually your going to want a bigger one anyways! lol i keep trying to justify a 300g... i really need that tank!

as for your parrot... feed it to the cat and keep the acara lol i hate parrots! looks like a goldfish that got kicked in the face! LOL j/k

yeah, likely if the acara is agressive towards the parrot, removing the agressor will reduce some of the stress off the parrot, and should bring it out more

yeah I am kinda leaning that way. would two male acaras be comparable?