Okay so the tank isn’t cycled? Also is it a 20 long or 20 high? I recommend you do methylene blue baths and see if that helps. Kanaplex is also a good medication.
If I'm seeing the white spots correctly, it just looks like some damage to the rays. If they get hurt/cut, they end up looking like that.
What kind of decor do you have? Goldfish are really good at scraping off scales, believe me, but they do regrow, and most of the time they're the same color.
That's good. Do any of the plants have sharp edges or anything? One of mine is especially gifted, she scraped some of her scales off on an entirely smooth rockI have just a few plants In the tank because most decorations at the pet store don’t have holes big enough for my fish to fit in loll