I am a NEW betta mommy!

I have 3 beautiful boys!! Our first is a blue-green male that we named
Mr.Fish. (actually our 3 year old named him that) Our second one is a Red male, I believe they called him a crowntail? His name is
Fireball! Our third is a black one with some silver/white in his fin. I think he was a half-moon?
Anyway our black one doesn't have a name yet!! And he isn't really showing much of a personality except that he does hide ALOT! He comes out to eat and then goes back into hiding.
I am thinking of naming him Shadow, due to the fact that we never see him.
But I would like some more input on names....
What do you think? And do you have any good names to suggest?
If I'm doing this right....^^^that should be our newest addition to our family

What do you think? Is he a Shadow or do you see something else?