Guppies live by a very simple equation: Boy guppy plus girl guppy equals baby guppies. Lots of babies -- a new litter about every 30 days. Because she can store sperm, the female guppy can produce new litters for up to a year, even if you separate her from males. If your guppy is in a family way, her appearance and behavior will tip you off when her time is at hand.
Bye, Bye, Love
Because males will chase, harass and exhaust her, the female needs to be separated from the boys as soon as you realize she’s pregnant. If you can’t move her to her own tank, equip the community aquarium with a false-bottom breeder box and put her in it until she delivers.
In a Family Way
Your pregnant guppy will develop a dark “gravid spot” just above and in front of her anal fin. As pregnancy progresses, the spot will become larger and darker. Her belly will assume a boxy, rectangular appearance and enlarge to the point that it looks as if it will burst when she’s about to deliver. If she’s in with the general population, the mother-to-be will take to hanging around isolated areas by herself.
The Blessed Event
Guppy pregnancy lasts for roughly a month from conception. First-time mamas deliver about 12 to 30 babies over a period of several hours. Veterans may gift you with 50 to 80 or more fry in a few hours.