I'm assuming you are asking how long a Molly carries her young inside her for. If that is what you wish to know then the answer is "It varies depending on the conditions she is kept in. A female Molly (Poecillia sp) usually carries young for 3 to 4 weeks but they have been known to extend this period for several months when conditions are bad.
27 days
There are many different types of fish. A "painted" Molly fish, refers to any Molly fish that has been dyed to appear as "painted" with markings.
This is going to depend on the type of fish; many fish, such as goldfish are egg laying, so they do not get pregnant. Other types of fish, such as Mollies are livebearing and their gestation is typically around 21 to 28 days
A molly fish can produce over a hundred fry in a month
Most of the livebearers have a gestation period of around 30 days. This of course varies with the temperature of the water.
Sometimes you can tell by looking at the fish's belly. Many times right above the anal fin you can see a black spot forming. This spot is called a gravid spot. Which tells you there are tiny fish developing inside the mother. However with some color types of these fish, it's nearly impossible to see this spot. Yo can also look at the general size of the fish. Take note of whether or not it's belly seems to be expanding. And if you have more than 1 molly, is this ones belly bigger than theirs? Odds are that your Molly is most likely pregnant, livebearers rarely waste any time in this regard.
They dont always die and its probaly because of stress of two many fish, not enough hiding spots, or other fish or diseases. By the way sorry about your dead molly. Hope this saves some fish' lifes.
A 20-gallon tank can comfortably house around 4 to 6 molly fish. It is important to consider the size and behavior of the fish to ensure they have enough space to thrive.
2 days
12 weeks after mating
Fry! They are tiny little black fish the size of a pinhead. Many baby fish are called Fry.
1 month and 2 days.