Illness/Sickness: Leucistic with white fluffy gills not eating

My Aleta has completely white, fluffy gills and is generally pale all over, her gills are usually red or pinkish if she is hungry. She hasn't eaten in about a week and a half and she can't keep her backside down, keeps hand-standing all over the tank. She is swimming about, though less than usual.

Aleta is 12 years old, I have had her for nearly half of my life, she is very important to me, and though I know she's not young, I want to do everything I can to help her feel better.

She eats beef heart, and has done for 12 years so shows no interest in other foods, I always cool her tank with ice bottles, temp is fine at the moment. She has never been fridged or had a salt bath so I am hesitant to try these things.

I can't post a photo as she is currently hiding in her favourite tunnel.

Please help if you can

She passed away.

I'm sorry for your loss. She was lucky to have you, since you obviously took very good care of her. I wish I knew something you could have done to help her at the end. You did your best.

I'm sorry for your loss. She had a long great life