About 200 live moina to start a moina culture.
Moina are much smaller and produce faster than daphnia. It's the best food source for betta, guppy frys because they won't dirty the water and can live in frys tank for days to ensure your frys always have food available.
Once you have a culture established, setup another for backup because they would crash eventually. Feel free to message me if you have question how to culture moina