Fertility at the palace.

So I set up a 20 gallon tank. Last week I was finally able to get some fish into it. I decided to get 3 platies since they are hardy and recommended for beginners. One did die, I got a refund. But imagine my surprise Saturday morning to find about 8-10 baby fish floating around! The gestational period for a platy is about 1 month, so she came to me knocked up. One baby fish (fry) has died already, but according to everything I have read, many fry die early on. I'm guessing the other adult in the tank is a male, because ever since she delivered the fry (apparently platies are live-bearers) the other guy won't leave the mother alone. Isn't that typical? The mother is taking care of nine babies all day and her man thinks she has the energy for a little somethin'-somethin'. Even if a few fry live, I will save scads of money on buying new fish!