Considering that these are social, I would say that as long as the tankmates are not big enough to fit in the parrot’s mouth and are relatively peaceful, just about anything might go. Some of the combo’s I have seen include plecos, yoyo loaches, Cory cats, and glow tetras. Considering that parrots may be shy at first, you may way to include a school of dither fish. This will make them more social.