If you are really worried, there are long gloves sold for doing maintenance in fish tanks. Some are thick enough to protect from spines and the like. Might be a good idea and it will give you peace of mind. Also, it will prevent any lotions, soaps, etc from getting in your tank from your arms. I definitely plan on getting some if I end up with venomous fish, and have thought about getting some now since my puffers bite. Knowing I have some protection will probably make me less jumpy when I have my hands in the tank.