That is an amazing link, by the way. I imagine that the guy who wrote it has a little apartment where every surface is covered with some kind of bug or some kind of baby fish. For easy reference, I believe he discusses:
Vinegar eels, microworms, bbs, daphnia, confused beetles, grindal worms, earthworms, white worms, livebearer fry, and snails. All with really detailed pictures. Fantastic. And a little gross.
After intensive research, I’ve decided to go for the microworms. They are arriving this week!