For one you need to be able to tell the difference between male and female.
Males always have the sword on their tail and are normally bright coloured or speckled. Females don't have the sword and look anything between whitey grey to orangey or yellowy even speckled.
If a female is pregnant you will start to notice her baby bump in a week or two. It is a good idea that you separate her or even better put in a few LIVE plants or hidey holes for cover so the baby fish can hide so they wont be eaten by their mother or father or anyone else for that matter.
Swordtails are live-bearers, they give birth to live fry.
they breathe through gills
It's a fish.
Swordtail is not a mammal, it's a fish although it gives birth. Another example like Swordtail is Guppy. Guppy gives birth but it's a fish.
A Swordtail is a type of fish that has a sword shape on their tail. Males have them but females don't.
There are guppies and mollies.
Tropical fish flakes
Swordfish, swordtail
yes it is....it is very popular for freshwater aquariums
Yellow Swordtail
A swordtail is a tropical fish and a goldfish is not. The swordtail would need a higher temp. than the goldfish. Depending on where you live it probably wouldn't survive the winter.
When they start having offspring.
no it will not but it would attack if it or it's babies are threatened
At about 6-7 months old