How soon can guppies multiply?
Females mature at about 3 months of age, perhaps sooner in a warmer tank. Males sexually mature somewhat sooner. The males will develop a modified, pointed anal fin called gonopodium, after several weeks. The male with the least desirable traits often impregnates the females, and all chances of controlled breeding is lost. This is a good reason to separate them before the male can develop his gonopodium.
