It's not a matter of "how old" but a matter of size. The danger is being eaten by larger fish. If the molly fry are fed well, given heaps of good water and swimspace they should be around 1 inch long in about 12 weeks. At that size they are usually capable of being kept with all but the large predatory cichlids.
Untill they are too large to be eaten by the other fish they would be kept with.
It is about to die or it is old or weak
6 mths
yes, as long as its old enough.
yes but it will only be used by the baby and the baby will have to be old enough to use it
As long as it's not still a baby, probably. :)
maybe in dragon years
3 to 4 years
When there old enough to eat grain
It depends how old it is. Mothers can eat a hurt or sick baby. If the baby is old enough to be separated out it may well survive if given the correct treatment and lots of TLC.
Simple. Buy a bitch, mate him and when his pups are old enough have your baby pee on his pups
Crayfish of the same sex are incredibly prone to fighting since they are very territorial animals. If you have a large tank with plenty of hiding places, it is possible that the two can coexist peacefully.
You have the baby. What do you mean what do you do. If you are adult enough to have sex, obviously you are old enough to have a child. Old enough maybe, mature...not so sure if you are asking such a stupid question.