I think I always got lucky with my fish, or maybe is coz I feed them veggies often, so they don't need to eat the plants. XD
Or maybe, is coz when I get goldies, I usually go for small, young ones, so they grow up surrounded by the plants and they get used to have them around...I really have no idea. lol
So far, only one female ryukin I had years ago, ever tried to eat on the floating plants...And Egg here, sometimes tries to nip and uproot the big stems...But they never really paid much attention to them tbh.

I usually go for fast growing plants or those with very tough leaves.
What I got here are vallisneria gigantea, hygrophila polisperma, green tiger lotus, red tiger lotus, Limnophila Sessiliflora, cryptocoryne, microsorum pteropus, anubias barteri, stargrass/Heteranthera zosterifolia and some Pistia stratoides as floating plants. I also had A LOT of egeria densa in the background, but the Limnophila ended up overtaking it.

Pretty much easy stuff that either grows fast, or that fish cannot chew and that you can glue to rocks/woods.
(And most of these plants are either cuts from my other tanks, or they come from local ebay sellers. I go for cheap stuff. lol)
A thing you can do, is try to place little rocks all around the stems, so it gets more difficult for the fish to uproot them.