Remember my post on "Lazy Platy"? Well now she's normal but she's chaseing/niping my other female platies! Catfish fight ! Catfish Fight ! No lost fins yet, how can I stop this?
Try adding more plants/decoration to block line of sight. You may end up just having to separate the fish as there may not be a way to stop it. Is she guarding a certain area? I don't recall if your lazy Platy was pregnant. Pregnant females about to birth hide out and protect an area before birthing.