Suitable Male For Black And Calico Platies?

[Kellene]

Hi! A few days ago, I found my male platy (don't know what kind he was) stuck to the filter. (His fin got nipped by a female molly and he got really timid, seemingly scared to go and get food from the surface, so I assume he died of starvation)
Anywho, he never paid much attention to the two female platies (Black and a Calico), or the female swordtails for that matter. I was  going to replace him, but I wasn't sure what variety of platy to replace him with. I was going to get a different species, like a blue mickey mouse or something,  so that I would get unique fry from the females.
Whenever I tried this in the past with platies, I never got any fry. Same with the mollies. The two male marbles only chase the female marble, and ignore the creamsicle females.
So, can the different varieties of platies cross with each other? Or when I look for my new platy should I try and find a Calico or Black?
I apologize for being so length, I'm just confused.

 

[the_lock_man]

The different varieties of platy are colour morphs, they aren't species. Any male platy will breed with a female in the same way that different ethnicities of human can have kids together.

I suspect that your females are having fry it's just that all the fry are being predated upon by the adult fish. This is very common.

 

[Kellene]

I know that they are all the same species... The thing is, my male (in both cases) showed a bit of interest in the females the first or second day (usually showing aggression towards one of the females).
Then they completely ignore them.
The females I'm pretty sure never dropped (in my tank, at least) because they never even looked pregnant. They were always skinny (yes, they were getting enough food) The Black female was kind of big when I got her, and I thought for sure she was going to drop. I've had her for over a month now, but she hasn't gotten any bigger or smaller, so I guess she's just "fat." She never hovered behind the plants like one of my swordtails did before she gave birth. I've had the Calico the same amount of time, and she stayed lean, but she has developed a gravid patch. But isn't that just a sign of being female? Are they, like, too young to breed? Both of them are about 1 1/2 inches long (so about 4 cm).
Thank you for your time