ratio is important because it keeps females happier and less picked on by the males, who constantly want to mate with them, whether the female is pregnant or not. keeping 2 or more females to a male insures that the harassment is spread out between them.

   oh, and i forgot to mention. the only problem with the larger ratio is space. remember that each female needs atleast 1 gal of water, as do the males. the females also drop up to 100 young at a time, although 15 or so is more common. depending on if you separate from adults/how many adults you have/what other fish are in the tank with the babies, you could end up with a 100% survival rate and end up with more babies to find space for.