As opposed to saltwater, which is pretty much the same in terms of chemistry all over the world, freshwater varies dramatically. Our freshwater fish come from diverse environments ranging from the hard alkaline waters of the African rift lakes to the soft and acid “blackwater” of the Rio Negro, or of Asian still backwaters and rice paddies. Fortunately about 90 percent of the fish in your local fish store were commercially bred and raised, and they are used to neutral water, meaning pH of around 7.0 and moderate hardness.
However, the water that you use for your fish comes from the tap in your house, and can vary tremendously depending on whether it comes from a private well, public wells or other public water sources. It’s very important that you find out the characteristics of your tap water, either by asking your water supplier or taking a sample to your local fish store to be tested. You need to know:
• pH – how acid or alkaline your water is
• Hardness – the minerals dissolved in the water
• Alkalinity – is the water “buffered” – does it tend to drop in pH
• Additives – most public water has chlorine and/or chloramines added to purify it
It is important that you find out these four water qualities before you even think about putting fish into it. Your local fish store should be able to test a sample for “The Big Four” listed above – or you can buy simple test kits to do it yourself.