swordtail fish :How old does a swordtail fish have to be before they are ready to mate?

Answer 1

The breeding age varies with such factors as food and water quality,water cleanliness, water temperature,and to a certain extent, genetics.
Here's the genetic thing. If you leave all of your live-bearers together in one tank,the fish that mature sexually at a young age (and smaller body size) will be the ones that spawn the most. This results in a continuously decreasing body size with increasingly earlier sexual maturity, with only one tank it's unavoidable. The reason for this is that the growth rate slows after sexual maturity. The way to improve the body size (and therefore value) of the offspring is to segregate the sexes, and cull these early maturing fish,(or at least keep them from breeding). At the end of several months,the later maturing fish will be fully grown and ready to breed,then the entire process can begin again.

Answer 2

between 3-6 months they can mate but the older they are the more babies they have.