The Gravid Spot in Fishes

In Live bearing fish such as guppies and mollies, the pregnant female develops a dark spot near the anal fin.  This is an indicator of pregnancy.  As the embryoes grow inside the female, the gravid spot becomes darker and more pronounced.

Observing the Gravid spot will give an indication of the stage of the pregnancy and the approximate time of delivery.

The Gravid Spot is most visible in female Guppies.