Iodide is an important element to both fish and invertebrates. For fish; iodine prevents goiter; a physical deformation. Crabs; shrimp; and other similar organisms cannot molt without the proper amount of iodine. Iodine detoxifies the oxygen produced by the zooxanthellae algae within coral skeletons. All of these important factors should insure that iodine is a key part of your supplementation. A special form of iodine that is very difficult to overdose; making it the safest choice for novice aquarists. It is important to dose iodine on a regular basis because carbon filtration and protein skimming remove it from water. Concentrated Iodine is best dosed on a daily basis (remember to divide the suggested weekly dosing volume by the number of days per week you will be adding the product to the aquarium); which will maintain an approximately stable iodine concentration in the aquarium at all times.