Thanks for all the advice! When I got the aquarium two years ago the Goldies were so small the gravel suited them at the time. But they have all grown and now two of them are definitely at risk due to their in increased size. Knowing this, when I upgrade to a bigger aquarium (within the next month or two) I will get some bigger rocks and try for a more natural decor. Maybe get some flat pond rocks to cover the bottom along with some aquarium sand. I will probably be upgrading to between a 30-40 gallon tank, which I know will still be overstocked, but is much better than their current 20.
I would like to find good homes for a few of them so they're not so overcrowded but not many people around here treat fish very well. Goldfish especially. I want to ensure they have a good home no matter what. Sometimes I feel like a bad owner

I wasn't prepared for goldfish. I kind of rescued them from the jaws of impending doom without realizing I was ill equipped to keep them.
I do my best though!