Aggressive Platies?

[-FighterFishh]

In my new 64L, I have two female platies (one white with black speckles and one blue). The blue girl is nipping at the other girls fins, and attempting to steal her food in the morning. Why could she be doing this? Would adding another platy help?
Thank you!

 

[nicklos]

Platys are an unusual bunch when it comes to aggresivness. It seems that the more platys you have, the more spaced out the aggression will be. I would at least get 2 more females.

 

[-FighterFishh]

Platys are an unusual bunch when it comes to aggresivness. It seems that the more platys you have, the more spaced out the aggression will be. I would at least get 2 more females.

Okay.
I was planning to buy two more, but I'm unsure if I want to as there are 2 babies in my tank which will be either swords or platies, probably platies though.
Should I wait for them to grow or get another 1/2 girls now? The babies are currently around 0.5cm long.