I have a female platy that has decided she is going to bully all of her tank mates. She does appear to be pregnant with a few fry but not many. Her litters are usually quite small. It doesn't appear as if she is doing any real damage to the other fish, which could just be because shes a platy with a small mouth. She is the smallest one in the tank and while that tank is normally super peaceful and easy going she is annoying everyone. She will literally swim around the tank and chase and nip everyone no matter where they are in the tank. All I can think is she is close to birthing? She has never behaved like this before though. I have put her in an isolation tank hoping that is all it is and she will feel secure. Any thoughts?