I have only silk plants for the new aquarium (obviously not ready for real plants yet--trying to figure out the fish!).
Once he's off treatment (I don't think plants like too much of any kind of salt, maybe a little epsom is ok? worth checking), you could try some wisteria (water lettuce). I leave it floating in Sid's tank, and he loves to 'hammock' in it. It's happy to live as a floating plant and will send down roots, which look kind of nice.
Demyx has a 'mat' of floating java fern - it's not quite as pretty as wisteria when left loose, but he likes it a lot better for its denser leaves (he is really wimpy and likes to hide a lot).
These are both easy plants to keep, don't mind low light and will support your fish near the surface, in my experience with them so far. Wisteria breaks easily, so I'm careful when fishing it out for tank cleaning or re-arranging. I did have some go very funky, I don't know why, in Demyx's tank - his is not filtered, Sid's is, so maybe that's a factor, idk.