The whole reason I have the hujetas is for their feeding charicteristics. I have one 10g quarantine tank setup with rosy red minnows, and another with guppy feeders. both are actually pretty nutritious, just stay away from goldfish.
One week I will feed guppies while my rosy's are in quarantine for that week, also so I can gut load them. Then the next week I will feed the rosy's while the new guppies are in quarantine. Its best to raise your own feeders, BUT the "hole in the wall" LFS I go to has VERY good quality feeders, and I quarantine them to watch for diseased feeders.
One bad thing with feeders, is that you want your fish to have a varied diet, so make sure and feed the feeders a good mix of algae wafers and flake RIGHT before you feed them to your hujeta, this will help keep him in the best health.
IMO they arent nearly as fun if not fed live food at least once in a while. Their temperment also changes (for the worse IMO) if completely cut off from live foods.