When will I know if paty's breed or not?

[Yodlem]

I could swear they are two different gender platies...if they breed, under what conditions will they breed?

[Zagz]

If they are two different species of platies they may not breed at all. Mollies do cross breed so it is possible they will breed. Livebearer's breed under almost all conditions, as long as the parameters are pristine.

The way to tell females from males are the bottom fins, females have fan shaped fins, males have more straight thin fins.

[Yodlem]

Originally Posted by Zagz

If they are two different species of platies they may not breed at all. Mollies do cross breed so it is possible they will breed. Livebearer's breed under almost all conditions, as long as the parameters are pristine.

The way to tell females from males are the bottom fins, females have fan shaped fins, males have more straight thin fins.

How could I tell if they are two different species?

[RoK]

Nearly all platies at pet stores are Xiphophorus maculatus.
Sometimes you may find the variatus platies. What Xiphophorus variatus look like:

[Yodlem]

Originally Posted by RoK

Nearly all platies at pet stores are Xiphophorus maculatus.
Sometimes you may find the variatus platies. What Xiphophorus variatus look like:

both of them are the ones on the left.
<------My avatar shows the male one

[RoK]

I'm pretty sure yours are actually the regular platies. The variatus have little to no black coloration.