you should also note, that depending on each persons allergies, and sensitivity to some things. While a lot of people have no problems with putting their hands in their tanks, other have many. Some people will have minor issues with their hands burning, to some break out in a rash. Some people can have a severe reaction if highly sensitive. And it is not just corals that can do this, Their are several venomous fish that can put a healthy person in the hospital. So it is very important to know exactly what you have in your tank and how it can effect you. If you are sensitive or allergic to bee stings or spider bites, Be extremely careful.