So if I simply get rid of him this wont be enough?Yes it is. Use Aptasia x on it or take the crab out and do systematic scrub downs. You have to do it a bunch of times without reintroducing the small microscopic spores of the aptasia back into your tank. Make sure you do it right or it will come back with a vengeance. You can always put the crab into the sump.
You can put the crab into the sump but more than likely if you have it inside your tank already, the chances are it’s already spread. They are tiny so you won’t really be able to notice them until they get bigger and the tentacles are easier to spotSo if I simply get rid of him this wont be enough?