Dropsy happens and heals at random, so some fish recover and some don't. Depends on their immune system. Like I had a betta two years ago, it took three months for its fin rot to go away, then suddenly the rot came back and after only two days the fish took flight to heaven.

All the best dude.

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I am a collage of unaccounted-for brushstrokes. I am all random. Excuse me.