it's like this,plecos don't eat plants too much if they are well fed.if you try and pretend that plecos only eat algae and plants then yes your plants are going to be a fishy salad bar pronto.feed your pleco a varied diet with algae wafers,frozen bloodworms,fresh raw(or parcooked)shrimp,zuccini,green peas(remove the skins first)and your pleco should never touch your plants.it's not a sure bet but it should stop you pleco from eating your plants.