Female guppies can get pregnant as early as one month old in a warm tank, although the usual maturity age is three months.
The key to understanding a guppy’s gestation period is knowing whether she is pregnant or not. It may be difficult to tell if a guppy is pregnant right away, although the gravid spot which is a dark spot near the anus at the back of the abdomen under the tail – will become darken and enlarge in pregnant females.
A pregnant guppy fish will also appear to grow larger with a bulky, boxy shape, but this may not be apparent until near the end of her pregnancy. Toward the end of the pregnancy, the small eyes of the fry may also be visible through the female’s thin, translucent belly skin, particularly near the gravid spot.
