It's not at PetSmart, but Atison's Pro is what I recommend. It's pretty easy to find on eBay, but you'll have to order it there as it's been discontinued in the States. The first ingredient is brine shrimp embryos, which seems to be what you're looking for, and the pellets are nice and small (they float well, too) so you won't have to chop up your boy's food anymore. Personally, mine goes mad for it, more than the New Life Spectrum pellets that I also feed him.
There's also an Atison's Betta FOOD
, with a blue cap instead of the pink cap on the Atison's Pro container. Don't get the "Food", it's nowhere near as nutritious.
This is what the container/packaging of the Pro should look like: