The hardest part is over. I got them feeding :)
I got a feeding response from my own frozen food, but they ended up spitting it out. I added some garlic and got a stronger response, but they still spat it out. I added a baby guppy and it was like all their Christmases came at once! The guppy was literally in the water for one second before being eaten. Now I just need to make sure they will reliably feed, then wean them onto something healthier and I'm all set!
I'm going to try to find something a bit more nutritious than guppys in the mean time, but for now they'll have to do. Maybe I can find some more of those baby shrimp :)