Ghost shrimp are the best. Set up a small tank or even tupperware container with a sponge filter. Gut load with marine flake food or pellets, I use Omega One marine micro pellets. You can even enhance them with efa and vitamins. I pull the ones I'm feeding and add brightwell aminomega and vitamin m to the container for 10-15 min before feeding.
Appropriate sized mollies is also a good food choice. Mollies are easy to keep with just a sponge filter as well. Regular feeder guppies aren't too bad, but they need to be acclimated for at least an hour so they don't just float to the surface.
What kind of eel; some eels enjoy fiddler crabs, again appropriate sized.
I feed all of my predators a live diet, and have for many years. As good as the debate is that a balanced "dead" diet is better, it really doesn't play in the real world. I keep dwarf lions and anglers and no one I've ever known have kept any of them long term feeding dead vs me keeping them on a live diet.
I mainly feed ghosties, a few times a month mollies, guppies in a pinch, once a month or so peppermint shrimp. These are the foods I have readily available. Some people can get marine shrimp and marine feeder fish.