I am gathering that you are talking about a red wag tail Platy, if you not ignor the rest of this post.
If you are then here is a little that might help, Xiphorphorus Maculartus ie. The Platy. There are about 40 differant variations to this fish, in the original form the colour was dark olive on the upper part and white on the bottom part, you have a red platy which could be a hybred of this. You can tell by the amount of rays on the dorsal fin, if it has 9-10 it is a form of the original platy. And it grows to about 1.6inch.
Xiphorphorus Variatus has 11-12 rays and grows to about 2.2inch.
A pregnant female depending on her age and size will give birth to 10-150 live young after a gestation period of about 4-6 weeks. i am not a great lover of breeding traps, the small boxes that sit on the inside of your tank. I think that this stresses the fish into giving birth. I would recomment either leaving her in the tank to give birth or keeping a small tank ready and useing that. The fry are about 7-8mm long but grow very quickly and they can reach maturity themselves after 6-8 months.
I hope this was of some help. If i am wrong with any of this information someone will correct me.
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