my female pregnant guppy is picking on the other three pregnant female guppies what does this mean??/?

Answer 1

Maybe she is being territorial. Is the tank big enough for all four females? That's a lot of fry to take care of - can you quarantine the aggressive female? She will need to be quarantined at some point anyway, since guppies will eat the fry.

Answer 2

I've had guppies many times, and they have all gone crazy eventually for whatever reason. One time they all started flinging themselves against the gravel. I think guppies are unstable, and anything can push them over the edge.

Answer 3

It's all about maintaining her rank and securing her unborn guppy. She wants to mark her territory.