culturing infusoria

Hello,i recently found out the tiny creatures of infusoria,and are interested to cultivate some yo feed my fish,and most places i search they are said to be for fish fry,is it ok for an adult fish to eat them? and what are the ways to cultivate/produce these creature.

So I don't have my fish yet, I'm getting them online due to an unavailability of them at the pet store. I will be getting 10, if they are adults I will start the breeding process, if they are young, I will wait. However the seller claims that they are adult fish. I will put them in a...