Increased Size: Pregnant female molly fish tend to grow larger in size as the pregnancy progresses. This is due to the development of the fry (baby fish) inside her body.
Darker Spot: As the female molly fish approaches the time of giving birth, a dark spot or gravid spot may appear on her body near the anal fin. This spot is where the fry are developing and is a clear sign of impending pregnancy.
Rounder Belly: The belly of the female molly fish will become noticeably rounder as the fry grow larger inside her. The belly may appear swollen or distended.
Behavioral Changes: Pregnant female molly fish may exhibit changes in behavior, such as becoming less active or spending more time hiding in the tank. They may also be less likely to feed as their appetite decreases.
Squarish Anal Fin: As the pregnancy advances, the anal fin of the female molly fish may become squarish or triangular in shape, indicating that the fry are almost ready to be born.