Because of its bulbous tentacles, no fish really is a predator nor will berghia nudibranch approach it. Majon wand which is costly does work, but best attack is chemically. The chemical I used to remove the Majano anemones is calcium hydroxide. It is commonly referred to as Kalkwasser, Kalk, and Pickling Lime.
Get the aquarium ready by turning off the power heads and pumps. This makes it much easier to apply the paste in an aquarium with no current. You also reduce the risk of harming nearby corals other than the majanos.
Then mix the powder with just enough water to make a thick paste almost like the consistency of toothpaste but just a little thinner and apply the paste over the whole majano using your syringe or pipette.
Turn the power-heads and pumps back on after 20-30 minutes and watch to assure none of the paste lands on any corals and if it does blow it off quickly with a turkey baster so they are not harmed.
Do note that concentrated Calcium Hydroxide is a medium strength base and will kill or severely injury anything it is applied to. Attempting to apply this solution to too many majanos at one time may have a negative affect on the pH and alkalinity of your tank and the paste will be harder to control when the pumps are turned back on
