Is tap water harmful to tropical fish?
Yes; untreated tap water is harmful to all fish. Tap water contains chlorine, chloramines, phosphate, heavy metals, and other harmful impurities, all of which water utility companies add to drinking water to make it “safe” for human consumption. While the human body can withstand these sanitizing poisons added to tap water, tropical fish cannot! That’s partly because tropical fish have extremely thin skin which will burn when exposed to chlorine and chloramines. This is why all tap water intended for aquarium use must be treated with something called water conditioner before being added to the aquarium. There are a variety of water conditioners available on the market and they will all effectively remove chlorine and chloramines. Most water conditioners need a few minutes to take effect (some need more). When adding fresh water to an aquarium that’s already set up (into one that already has fish in it), I put the tap water into a clean bucket, then add the water conditioner, swirl the
