I have read about their carnivorous nature in a book. It is pretty old.
I do give flakes and granules, as well as worms to my angels. They are well fed, but always hungry!
I will buy lettuce for them now, maybe they will leave the plants alone. The main thing for me is not to get them poisoned.
As to that plant, I only bought it for floating purposes - to give a little shade for the neons. Then I read that it can be planted - and you know the result.
There is another floating plant - salvinia (?)in my tanks, but nobody is interested in eating that, although they call it 'cabbages' in local shops.