Mine like bloodworms, regular flake food, algae pellets, sinking catfish food (not sure of the brand, I can look). What you want to do is cute everything into itty bitty peices, I've noticed that they don't even try to eat anything that won't fit in their mouths. I put mine (the tablets, not the worms) into a blender and it diced them to just the right size.
Yes, they are nocturnal so you will have best results feeding them at night, I feed between 7 and 9 o'clock, that works well for me.
Another tip is to drop to food into the water pouring out of the filter, that will push it down into the gravel faster, so they'll have an easier time getting to it.
Good luck, and they may be eating when you aren't looking, just keep that in mind.
