It's just a little aiptasia. There is no need to pull your fish out of your display tank.
You could put some vinegar in a syringe and inject it with vinegar. You could also use Joe's Juice to get rid of it. There's also the option of a kalkwasser paste. Now a days, you can even laser burn it to death LOL.
Taking your fish out of your display tank and putting them in quarantine stresses your fish out and causes unnecessary harm...