Guppies are livebearers, which means that they give birth to live fry instead of laying eggs. Female guppies are capable of breeding every few weeks because they are able to store sperm from males for several months. This means that a female guppy can mate with a male once and then give birth to multiple batches of fry over the course of several weeks, without needing to mate with a male again. Once a female guppy becomes pregnant, it typically takes around 4-6 weeks for the fry to develop insid