One of the manifestations of this disease is an insufficient amount of minerals. Fish absorb dissolved minerals and microelements they need for growth and development through gills and skin. Large fish require a high amount of minerals. In oxygen-rich water the amount of minerals and microelements decreases as they precipitate. The amount of minerals and microelements can be increased by constantly performing water changes and adding mineral supplements. Soft water is required for successfully breeding and keeping fish. For this purpose, many aquarists use reverse osmosis water or water from an ion-exchanger. As such water does not contain minerals and microelements, fish may develop diseases caused by mineral deficiency. Minerals and microelements are particularly important for young fish.