Hi, I am so sorry you didn't get an answer sooner.
I would imagine with the sound of the fish's condition she passed? How are the other fish?
The biggest thing would be to make sure the tank water is is perfect parameters.
How long has the tank be set up?
How long has this fish been in the tank
If the tank is not cycled with a colony of beneficial bacteria living in the filter media, then you will need to get the water to a safe level.
What is the ammonia,