Goldfish and Aquarium Board Articles
Water Quality
By Betty

Happy water is the key to happy fish.

Just because your water looks clear doesn't mean it's happy!

The very first thing to do if something is wrong with the fish is to ALWAYS check the water parameters and if out of whack, do a partial water change. When doing partial water changes, always use a water conditioner that detoxifies chlorine (at minimum) and heavy metals, and match the temperature of the change water to within a couple of degrees of the tank.

Ammonia: should be 0ppm.

Symptoms include: irritation, flashing, black areas, frayed fins, darting back and forth in the tank in uncontrollable spasms, spinning in small circles, and finally laying on the bottom

How toxic ammonia is in your tank depends on your water temperature and pH. Higher water temperature and higher pH make ammonia more toxic. If you pH is 8 you're going to have to work harder at keeping ammonia levels low than if your pH is 7. In general with:

More detailed information on ammonia toxicity, pH, and water temperature is here.


NitrIte: should be 0ppm

NitrIte is toxic. It enters thru the gills and binds up the red blood cells keeping them from being able to carry oxygen. Salt helps protect against nitrIte poisoning because the chlorine in it competes with nitrIte for uptake thru the gills. You should not see detectable levels of nitrIte in an established tank. If you are detecting nitrIte in an established tank, you need to reexamine your filtration, fish load and husbandry practices.

Symptoms include: Oxygen seeking behavior. e.g. rapid gill movements, staying near the top of the top, gulping air, etc, lethargy, gills are brown instead of bright cherry red.


Nitrate: 0-40ppm (optimal)

Symptoms: can cause flip over problems, dilated blood vessles in fins, decreased immune response.

Treatment: partial water changes will help to bring nitrAte down to safe levels. Adding fast growing plants may also help keep nitrAte from building up.

pH/KH: 7.5-8.3 (Optimal range)/ 120-300ppm

If your pH is lower, it will have a tendency to slip down over time. If pH gets down to 6, it can be deadly for your fish and for the bacteria that keep your water happy. The pH of blood is around 7.4 and there are only a layer of two of cells between the fish's blood and the water. Rapid swings in pH or extreme pH can cause the blood to get too alkaline or too acidic.

Symptoms include: irritation, flashing, frayed fins


General hardness (GH): 100+ppm (optimal)

These are the dissolved minerals in your water, primarily calcium and magnesium. Goldfish can tolerate a wide range of hardness levels, and generally your source water should be fine unless it's really really soft (low GH). GH helps to keep your pH from getting too high and aids in the fish being able to maintain proper fluid balance.

Water test kits for monitoring your water quality.

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