they get larger than that I believe. Closer to 8 inches. I'd say 29 is the bottom end of the scale for keeping a parrot I'd go larger especially a pair. They are hybrids and like many hybrids tend to be infertile. The male has a 95% chance of being infertile. The female is fertile and can be bred with other fishes to further the hybridization. You can try pink convicts they make very attractive and extremely hardy fry known generally as jellybean parrots.
Oh and this should go in the hybrid forum. Some don't take to kindly to hybrids.