Is there a reason my platies are staying small?

I have two plain red platies in my community tank, I've had one in for three almost four months and the other for about two. They've both gotten a little bit bigger but are still half the size of my other platies. Is there some reason they're staying so small?

 

Plates can take a while to grow to their full potential, I wouldn't be to concerned as long as the tank is stocked properly and the waters good.

 

It may just be the type of platy. Same species but different types have different sizes.
All my mollies stay small but I have one that's a good 2 inches. Just a varied size. Very pretty platies if I may say.

 

Thanks guys! They're my sisters favorite so I was just wondering.

 

Thanks guys! They're my sisters favorite so I was just wondering.

Aw trust me I understand! I'm so attached to my babies little things still freak me out. My big molly is the only surviving baby of one of my balloon mollies so you can imagine my surprise when she got 3 times the size of her parents. I still can't figure out how she birthed her. lol

 

Haha that's funny. I knew I was buying them young when I got these too but I figured they'd get bigger quickly. I can still barely tell if they're male or female lol. I'm just hoping neither of them get pregnant while they're this small because I would never be able to tell lol

 

So I was just googling it, is it possible they are coral dwarf platies? They seem like the most likely suspect lol

 

the yellow one is female. if you can manage a better pic of the fins on the underside of the orange one, I can see if I can tell

 

Oh I can tell the bigger ones. I know how to sex them the little ones are just so small lol, plus when you can actually see they're in the light so it's almost transparent.