The Discount Leisure air disk is a high quality air stone for adding large ammounts of oxygen into your pond or aquarium. Oxygen is essential for all aquatic life and when connected to an air pump(not included) large ammount of oxygen will be added to the water, this will not only be beneficial to your fish but also to your filter system. Friendly filter bacteria also need oxygen to survive and with the extra oxygen produced from this stone your biological filter performance will be improved.