You would have to get a pleco that was already a minimum of 4 inches, as the blood parrot would slurp a smaller fish like spaghetti. I have two bristlenose plecos growing out a bit in my community tank until they're large enough to go into the parrot tank.
Personally, I don't think a pleco is right for you at the moment. You already have pictus, which require a larger school, if I'm not mistaken. That takes care of the bottom of your tank. The pleco would get run over.
Plus, your tank is pretty small for what you already have. You'll need a larger tank for the parrot and the pictus. The pictus really needs about a 55 gallon tank.