I wouldn't necessarily say that. Royal grammas are relatively sedentary protecting a cave or a rock crevice. I think the more common victims are those that graze constantly like tangs or angels and they get a little too close. I also suspect other common victims are atlantic fish who aren't familiar with haddoni's deadly stings. Haddoni don't have long sweeper tentacles and are pretty sedentary themselves. I have zero worries about my royal gramma with my carpets. My banggai cardinals, on the other hand, tempt fate with my giganteas literally swimming in the middle of the folds... One way to minimize risk is to let the RG find his cave and put the carpet on the opposite side of the tank out of the main swimming channel(s)/feeding zone(s) of the fish.