I woke up this morning to discover one of my female platys dead and covered in some sort of white cotton type slime. She was my first fish loss in well over a year. She was stinky upon removal. Can anyone tell me what that slime is and offer any ideas as to what caused the death? I performed an immediate 30% water change and all the other fish appear to be doing fine. It is a well maintained 29 gallon planted community tank.