Same as your story. Moved everyone to a larger tank using all the right steps. Everyone is happy and growing. Shortly after the move she sat on the bottom and wouldn't swim. Then she stopped eating. I tried a variety of foods and remedies but she just got worse. Finally had to put her out of her misery. The clove oil does work quickly and apparently painlessly. Good thing, that was almost as bad as the last trip to the vet with your dog.
This is what she looked like.
Wow she had some really nice fins...Actually I think your she was a he. But it had way nicer fins than mine. Those fins are amazingly long! Its awsome.