Sunset Hygro

I recently set up a planted discus tank which includes some
sunset hygrophilia.  While the plants are all thriving, my juvenile
discus like to munch on the new growths at the top of the plant!
Am I not feeding the poor little fellas enough or is this a plant
I should not keep in this 85F degree tank?

Any help would be appreciated.

Tyson Lee
tyson at phoenix_net