Well it may brighten his colors on the surface but genetically speaking it has no effect. What I mean is, if you were to breed him the fry wouldn't have more/less wash because of feeding the hikari.

1Fish, I've got a question on red wash again. Does colour enhancing pellets increase the red wash in bettas? I've been using Hikari Betta Bio-Gold and the red wash in my betta seems to have increased. Does it really affect or promote the red wash when I feed Hikari Pellets?

Without knowing the background of the fish it's hard to tell. In general though if you want to get rid of the red wash it's best to get a female with no red who comes from a line that is not showing red. You may still get a little red but if you breed carefully in successive generations you will probably begin to see less red, although you may see throwbacks once in a while. If either of your breeders come from marble or multicolor lines there's really no way to tell what you'll get.

To get butterfly the best way is to find a female who also exhibits the butterfly pattern or to get a sibling sister to the male with a butterfly pattern. You'd be better off breeding him to a blue female than an opaque, depending on the type of opaque, however that would still be an interesting cross.

Hey 1Fish!
I thought you are good in colour genetics, so I want to ask you some questions. :)
Questions on red wash and butterfly bettas. My turquoise Halfmoon has red wash on his anal fins and a little on his ventral fins. I've been wanting to breed him with another turquoise/steel-blue/royal blue female with no red wash. Is it possible for the fry to have no red wash?
About the Butterfly question, how do I get a butterfly fry(blue) out of a spawn? Do I have to need a Butterfly male(Halfmoon) breed with a normal royal blue/steel blue/turquoise female? OR should I breed a Blue Halfmoon male with a Opaque White or Platinum female?