I completely agree with rivkah's method. I also am an avid fish keeper and have an African Fat-Tailed Gecko. 3% bleach solution, sit, rinse until you don't smell bleach (if you're still concerned you can fill the tank again with water and add water conditioner and let that sit, rinse) and let it air dry. I also know of pet stores that clean their tanks/decorations in the same manner.