- Size and Shape: Pregnant mollies may appear noticeably larger and rounder, especially in the belly area. Their bodies may become fuller and more distended as the pregnancy progresses.
- Dark Spot (Gravid Spot): As the pregnancy advances, a dark spot or gravid spot will become visible near the anal fin of the female molly. This spot is where the fry (baby mollies) will eventually be released. The gravid spot darkens as the pregnancy progresses and can serve as a reliable sign of pregnancy.
- Behavior Changes: Pregnant mollies may exhibit changes in behavior, such as becoming less active or spending more time hiding or resting in secluded areas of the tank. They may also show increased appetite and consume more food than usual.
- Coloration Changes: Some female mollies may display slight color changes during pregnancy, such as becoming paler or developing more vibrant colors. This is not always a reliable indicator of pregnancy, but can be observed in some cases.
- Rectangular Body Shape: As pregnancy progresses, the body of the female molly may take on a more rectangular or box-like shape due to the developing fry inside.
- Increased Caution Around Males: Pregnant mollies may become more cautious and avoid close contact with males as the pregnancy advances. This is because the males may attempt to mate with the pregnant female, which can cause stress and discomfort.
- Nearing Release of Fry: As the time for releasing the fry approaches, you may notice the gravid spot becoming even larger and darker, and the female molly may spend more time near hiding places or plants.
Pregnancy in mollies can last anywhere from 4 to 6 weeks depending on the species and individual fish. After this period, the female will release the fry, which are live-bearers and appear as tiny, fully formed versions of the adult mollies.
By observing these signs, you can determine when your molly fish is pregnant and prepare for the arrival of the fry.