Unlike tap water or spring water, distilled water has gone through a process that strips it almost completely of all minerals. Like RO water (reverse osmosis), it is essentially pure and no longer contains any of the trace elements that would be found naturally in water. Fish kept in distilled water over a period of time may show signs of lethargy or color loss. Most aquarists … [Read more...] about A Warning About Distilled Water and Betta Fish