Polar blue parrots are short-bodied Honduran redpoint convicts. They are not hybrids with red parrots, despite what you might read online.
Regular convicts can hit 6" for males and 4" for females, but since the polar blue parrots are the smaller HRP species and short bodied on top of that, I doubt you will ever see one much larger than 3".
Here is a pic I found online from MYAS's Youtube channel.
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yupWow that's actually a cool looking fish. Not at all what I thought one would look like. So the polar parrots are truly Honduran redpoints with a shortbody gene/deformity then.