Minnows are small fish that can grow up to about 6 inches max. Their prey are almost all aquatc animals bigger then them. Water dogs, salamanders, turtles, and even other fish. I keep water dogs so i decided just to breed minnows so i dont have to buy em everytime.
Process.
The process is really quite simple. You should probably have a 20-50 gallon tank depending on many you want. Fill the tank with tap water and either let it distill overnight or add de-chlorinater drops to the water. Next you will need a filter and an air pump. Or something that does both.
How to get the minnows in the first place.
Fishing bait stores sell them for about 2 dollars a dozen. Also ive known Petco to sell them as feeder fish. I wouldnt worry on try to get males and females, just get a whole bunch and chances are that their will be a mix of both.
Habitat.
Just an empty tank full of water. But to assure that they can lay their eggs, get a nice piece of drift wood so they can lay their eggs under it.
Temperature should be fairly cold. anywhere from 55-65 F is good. Monthly water changes might also do them some good.
Thats pretty much it. Let them grow to the size you want and feed them to your pet. Also bait stores and pet stores will pay you for them if they are looking to buy more.
Hope this helps - Jason