Clowns usually dont eat plants. They do hole-punch them though, for whatever reason. So far my little hole punchers havent caused enough damage to say so though, maybe I'm lucky. Adults are known to be able to uproot most plants, even being able to pry Java Fern from driftwood and rocks in there never ending search for food. I hope mine stay plant friendly as I am setting up a quite large plant tank for them.
they like the new leaves for some reason. I have an older sword plant that they peck at occasionally. They don't bother the older leaves as much. If I get a new leaf, they chew it up as soon as it opens.
Mine have trouble pulling my plants up since I bought the weights.