I had a few neons in with goldfish briefly. 1 got eaten. In my opinion, any fish small enough to be eaten will be. This includes platties, etc. My wife's fantail can take an entire algae wafer in its mouth and i am pretty sure it is not fully grown. Plecos and koi work. The goldfish will eventually try tasting guppy tail even if they don't eat the whole fish. They taste everything after about a year including fingers. A philodendron will survive goldfish but the leaves are all outside the tank. Philodendron don't need any care and hardly any light. I planted mine by removing the top from a gravel filter riser tube and inserting a cutting 2" in the water. It will start growing roots in a week. Fancy goldfish may tear fins on them if not in a tube. Bamboo works too but goldies snack on the roots more. None of the other plants I have tried survive as the fish grow. I do want to try duckweed but our 29 gal is overstocked with 2 goldfish and a Pleco. I doubt I could get enough duckweed to survive the first day.