Note the abdomen of the female. If it seems to you round and large, it is possible that your fish is pregnant. However, this figure may not be accurate, because you could just overfeed their favorite.
Remember when you found out rounding of the abdomen and observe the female for about two weeks, while not overfeed her. If you see that your mollienesia does not eat very much, but my stomach continues to grow, and her rounded hips, then you can safely be assured that soon it will bring you completion.
Pregnancy at mollies is about a month, sometimes, the fry are born a bit sooner or later. To isolate the female separately, we have a week before delivery, so until that time, it is necessary to provide peace of mind. Watch the fish every day and protect it from stress. If it suddenly begins to irritate the male, put it on some time in another place.
Watch the behavior of females. The closer the birth, the sounder becomes the fish. She starts to hide in the grass near the bottom, a long time may be hiding in the upper leaves of plants or driftwood. Her stomach by this time acquired an incredibly large size and became like a rectangle. In this case, you should isolate the fish in a specially prepared place for her and to wait, when will begin to appear fry.
In any case, do not replant a pregnant Molly in new water, otherwise it might not give birth or give birth to weak, if not dead fry. Water you have to take out of the tank in which before there was a female, then a partial water change and add a new one. Although the appearance of the fingerlings is not very long, and water does not become contaminated. After all the fry are born, the female is transplanted back to the others, and the offspring left in place as long as the fish will not grow up.