I personally think it's ok when my O attacks the roots. Part of the reason I put them in there is to entertain my fish otherwise i'd just create a pothos-sump or just put them in the HOB. Though I typically grow lots of them around the house so that I have a ready supply to add should he damage them too much.If the oscar ever starts attacking the roots then let me know, I know of a way to make it so that he can’t get to the roots.