Anubias might do. Much tougher leaves, and they often grow algae, which usually appeals to herbivores. Duckweed is another many plant eaters like, and grows very fast. So does Azolla, if you can get some. Needs more light than many floaters, but will turn a lovely red if it gets the light.
Given they like moss, which is soft, you can also try growing algae for them, on rocks. Put rocks in a shallow pan, or a jar, place in very bright light for as many hours as possible and wait for the green fuzz to grow. Drop rocks in the tank until they clean them off, then drop back in the algae farm to grow more green fuzz. Water only needs to be topped up and cover the rocks. Rough texture rocks grow more algae, I had the very best luck with marble chips and ceramic filter media. Smooth or polished rock won't grow much if any.
