I am far from proficient with the dwarfs. I have a few pygmies left from a purchase last summer. I think I got it figured out now.
When they are very young they are so small, I would feed them fry powder. They can have some trouble eating. They also must be secure and not be housed with any fish that will take delight in gulping or nipping them. When they are bigger they do ok in a community tank.
I am feeling confident enough now that this spring when it warms I will get a new school.
They are fun to watch. Cute little things, but not as interactive as other Cories.