Jus watch her carefully whatever you do, bcause if she offloads her fry into your main tank, it will be difficult to get the fry quick enough, because guppy fry are limited on speed, and they can be really, really, REALLY small, just because guppies are one of the smallest livebearers...
But anyhow good luck with them, it feels really rewarding when getting new fry, trust me, i just got ten new swordtail, and i never felt so proud of myself and honoured my fish are giving birth in my bedroom
