Breeding (more coming soon)
Guppies are livebearers not egg layers. The males need to copulate with females to impregnate them. Interstingly, once a female is impregnated she can store up sperm and even in the absence of the male continue to have a few drops (= batches of babies) in the months to come. The gestation period for a guppy is usually 28-32 days.
In order to maintain fancy guppy quality different strains are kept in separate tanks unless the purpose is to do an outcross. In addition, quality will quickly go down if you allow random males to mate with females since it is generally the smaller, faster, smaller-finned males that get to the females first. Many breeders will keep tanks of virgin females so that when they come across an exceptional male they can breed him to these females and be assured that he is the father. This method ("unnatural selection" or domestication) is why such emendous progress has been made converting wild guppies into large colorful fish with exceptional finnage.
Swim to Home Page