I tried burning it off with a match, but the match kept going out as soon as I put it in the water. :debi:
Seriously, a syringe works good. I'm not talking about the type with a needle, but one that comes with a test kit. Just be careful to not touch the aiptasia with the syringe or it will close up before you have a chance to squirt it. The small amount of juice used won't affect the tank. Just don't get it directly on anything you want to keep. I don't know from experience, but I suspect it could hurt a coral.