When I first built my pond I stocked my first FHM about 2 weeks after filling and it was at night. After releasing the minnows I was watching them swim off when I spotted something else. My first thought was a bullhead fry and then I realized it was ferry shrimp.
In the western 1/4 of Kansas we have very high numbers of Playas and they are of course dry most of the time except after a good rain (not often here) and most contain ferry shrimp. I've never tried to raise any but it's amazing that it can be dry for several years then get a good, heavy rain and the Playas are full of ferry shrimp in just a few days.