Helpful, as always!
Tubifex worms are not the kind of worms that can be purchased easily here, but some freshwater fish breeders cultivate them for themselves.
They can be raised exactly the same way it's done with blackworms.
One friend of mine, for instance, breed them along with daphnias . They settle at the bottom, feeding on decaying matters.
I myself used to raise tubifex in shallow tubs and vermiculite as substrate, feeding them on oatmeal or fish food. I used to put the containers inside a bigger one , full of ceramic tiles and a small water pump circulating water from the bigger to the smaller, overflowing back.
Thank's for coming by!