Mollys are community tropical fish and should be kept with others. That being said the basic rule for keeping any fish healthy is 1 inch of fish needs 1 gallon of water.
10 gallon
Right at 14 gallons
Mollies can be kept in quite small aquariums; probably down to about 5 gallons in size as the absolute minimum.
It would not kill the Molly, however it would seriously harm the Molly and shortly after the Molly would have very difficult challenges to live.
There are several species of Molly. The common black/spangled molly grows to around 2.5 to 3 inches. If you folow the basic rules of sucessfull fishkeeping which are. ":- 1 inch of fish must have at least 1 gallon of water. :- Every tank must have a permanently running 'cycled' filter. :- Every tank must have at least 50% of its water replaced every week." A single Molly needs at least 3 gallons of water.
You should wait until the fry are about 1/2 to 3/4 the size of the fish in there or else they are likely to get eaten.
Because they're tired.
I would suggest upgrading to a 10 gallon tank.
Intrusion..!
Molly Moore throws right.
Molly Mallon has written: 'Your child's right to read'
Every fish will make your tank dirty because every fish puts out waste.