The blog post I linked to mentioned Malaysian Trumpet Snails, and I think these would do best as they aerate the substrate for you.
My blackworms seem to be thriving on a diet of mulm and any decaying Indian Almond Leaves I pull out of my other tanks. They will probably be difficult to remove, as they bury into the substrate. You could also you bloodworms if you can find somewhere that sells them live.
I think I have copepods or something similar in some of my wild betta tanks. There's lots of nearly microscopic white things skittering around in there. My betta fry seem to like eating them. I don't know how they came into existence, but I think they like the leaf litter and wood I put in.