He's a hard one to name. Or, maybe he isn't, but I just haven't found the right name yet. He's one of those "quiet" bettas, though he still is active and flares.
I have a boy that has the same coloring and his name is Piglet (from winnie the pooh). He acts like a piglet and is colored like Piglet. Sherbert also comes to mind, or Raz, short for Raspberry :)