I know you want to get rid of it but that actually looks really nice lol. No sarcasm intended and I know that your plants will ultimately suffer but that looks beautiful to me.
LOL, believe me that's one of the reasons why it's gotten so bad... it started out as a nice little patch on the driftwood, looking like a lush moss. Well I let it be since I liked it there, and that's when it started spreading to the leaves
If it only grew on the rocks and driftwood I would love it.
Ok, what about floating plants? I know duckweed won't work since the fish will eat it, but are there other hardy floaters that goldfish won't eat? I'm hoping they will block out some of the light and soak up some nutrients...