Abstract: An internal corrosion prevention anode device and method for retrofitting an existing fuel storage tank of the type having one or more low points, includes inserting an anode through an opening formed in the top of the tank. The anode is formed having a rounded shape so that it will roll to a low point in the storage tank. An elongated electrical conductor is attached to the anode, which conductor has a sufficient length for extending from the top to the bottom of the inside of the tank and has sufficient flexibility to permit the anode to roll to a low point in the tank. A cap closes the opening in the top of the tank and electrically connects the elongated conductor from the anode to the top of the storage tank.