I have a question. How does one tell if their guppy is preagnent? I just recently got a male and female guppy and today, he was flashing his tail at her and following her arround. She already has a big tummy, but she was like that when I got her. I was also wondering how long their gestation period is. I.e. how long after mating do they give birth? I hope someone has some answers for me. Thankx.