Zëbulon:
My betta has become listless, won't eat and just rests below the
surface of the water. He does react if I approach the tank but he's
not feeling well. Part of his fin is gone and a bit raggedy, he also
has a white circle on his side.
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If he were my fish I' b be using Quick-Cure.

Is the white circle fuzzy or flat?

Flat as best I can tell, looks like a donut.

I didn't see Quick Cure at the pet store.

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Mac Cool