I breed Guppies, and if you have several females, you can keep a ratio of about 1 male to 2 females, even higher sometimes. Its slow starting, but my guppies have 20-30 babies each drop. Get some java moss for your breeder tank, because the guppies like to feed on thier babies! The java moss will provide cover, and if you have a good 4 to 6 females, you should have more fish than you know what to do with.
Do danios breed liek that??? I saw the post right before mine.