maybe the ends of your plants are just dead and every fish tens to eat dead ends... i had that question for years because all my fish where carnivours, till i added a good ferteliser and every fish stopped eatting my plants...
BARBS, i had a 30g planted and i had to put my 5 2-3" tinfoil barbs and they ate evey single last plant down to the stem in on night, i was glad i sold them then, but i miss them now, i cant find any other ones big enough to live with my arow
all of the fish in your tank will supplement their diet with vegetation. you need to make sure your providing enough nutrition and keeping them well fed and it shouldnt be a problem