Female Danio: Ulcers? Bacterial infection?

[FinAgain]

I noticed a large lesion on my female zebra danio's side about 9 days ago. I relocated her to a hospital tank and have been treating with Melafix. Now another lesion has opened on her other side and I can see THROUGH her. She's still eating and active and I'm stumped. Any ideas? Advice?

Additionally is it time for euthanasia? She's 3.5 yo.

More blurry, somewhat gruesome pics here: https://imgur.com/gallery/eDIbe

 

[nirbhao]

Yes on the euthanasia.

 

[FinAgain]

Thank you. It is done.

 

[nirbhao]

Sorry for your loss.