Hello jen...
The female Guppies are raised with the males, so they're all pregnant by the time they get to the pet store. Since you have females now, you never need to buy males. You'll get plenty in the next batch of fry.
You don't need to move your females from the main tank. It's stressful and unnecessary. Just start feeding all the fish a little more and more often. It's been my experience with "Livebearers", that well fed adults show little or no interest in the fry.
Don't forget some floating plants. Anacharis (Elodea densa) is one of the best. Good for the fry and the females to nibble and for hiding from the rest of the crowd.
As for food, go with frozen. It's more nutritious, because there are no additives. I feed frozen brine and Mysis shrimp, beef heart, plankton and krill. Also, add a little minced garlic to the menu. There's not another veggie available with more vitamins and natural antibiotics. Don't fret, the garlic won't make the water smell.
B
