The front of his head will never turn completely red because he doesn't have the genes for that to happen. If you feed him Hikari Blood Parrot food it will help the red he has become more intense. He could develop a few patches of red across his head but realistically there is a 1% chance of anything more then that happening. If you want to try a less natural approach to bring out red you can feed him Ionic. But Ionic food contains hormones.