some people will not put their hands in thier tank without wearing long gloves. there are various reasons including prevention of exposure to toxins. if you have scratches or wounds of any kind, this is probably the safest practice whether or not you have zoas/palys in the tank. there have been many claims of nasty bacterial infections of wounds after working in fresh and salt water aquaria. also, many people believe that the oils on our hands (as well as anything else that may be there) can be harmfull to the critters in the tank.