You may be overfeeding it, Fish are often given too much food even if they will eat it. It is recommended you feed them however much they can eat in about 5 minutes only once or twice a day. Be sure to clear out uneaten food from the tank as it may cause the water to get cloudy. Also if you are talking about goldfish they are in general just a dirty fish that does that a lot.
That's what they do. The time to worry is if they stop pooping.
no
by pooping alot
If you have a male and female Platty together I can guarantee that the female is pregnant (gravid) no matter what you think.
pooping blood
she could be pregnant
There is no reason to do so.
Yes, they can.
They can be pregnant (gravid) at 3 or 4 weeks.
Defication has no direct meaning that you are or are not pregnant. If you are continuing to have your period that you are not pregnant, but if you are late you may wish to consult a doctor.
Answer It is the platy's waste.
If I was you, I would go to the vet to give it a chech-up.
You should probably transfer it in a cup or trap it. ;)