Decorator crab vs Kenya tree
 

Decorator crab will not leave Kenya tree alone. Kenya tree doesn't seem to mind but at this point the crab has removed about a third of the limbs in 6 weeks and I now have 4 Kenya trees. Will he ever stop?

No. Banish him to your sump

The sump is where all crabs belong, or in the ocean where they were collected, accept for scarlet legged hermits.

Nope. Decorators take everything apart and your tank is going to end up as a Kenya garden. You can keep him in there if you don't mind, of course.