fish eating roots on plants

[waxmuseum]

Hi Im wondering if anyone has any ideas on how to stop dwarf gouramis from eating the roots of my plants.
The plants are presently tied to rocks and are trying to root (the guy at the fish store told me to do this with them)

[YawShinLeong]

Rightly they should leave the plants alone. However with the roots tied to rock, I suppose it is "exposed", hence if you can conceal the roots via means of strategic placement of rocks,that might be helpful.