SInce Heros are considered primariily herbivoroius cichlids you may need to expiriment to find that plant your particular individuales find distasteful.
I agree that many herbivores find java fern, and Anubius may be one of the the best choices, (So.might be bolbitus, another African water fern). Anubius left, java fern right.
My herbivore cichlids had a taste for tender dandilions and romaine lettuce, so they preferred that to rooted plants.
So offering tasty substitues might help.
https://youtu.be/SPgRGQi0r1A