Do Nitrates Kill Goldfish?

Water parameters in an aquarium are incredibly important. If the water is not tested regularly, it will be impossible to tell by scent, color or any other method whether the water is safe for the goldfish living in it. High nitrates can contribute to the decline, or even the death, of any goldfish.

  1. What a Nitrate Is

    • A nitrate is the byproduct of a nitrite, which is the byproduct of ammonia. Ammonia is a chemical present in goldfish feces and urine, as well as in other rotting matter in the aquarium, such as uneaten food, rotting plants or rotting aquarium life that you may not have noticed yet. The beneficial bacteria that are created by cycling an aquarium eat the ammonia and excrete the nitrites. The nitrites are then further used by these beneficial bacteria and come out as nitrates. Of the three, nitrates are the least harmful.

    How Nitrates Affect Goldfish

    • Nitrates, like nitrites and ammonia, are present in aquariums from the beginning of a cycle until the cycling is finished. High levels of nitrates make the water hard for fish to breathe because it takes up room in the molecules that oxygen and other necessary types of breathable air should be occupying.

    Testing Nitrate Levels

    • Ideally, nitrates will test at 0 when you dip your testing strips in the aquarium water. Anything above 1.0 is considered to be dangerous by many long-time goldfish keepers. If the problem persists after a 25 percent water change, you will have to increase your water changes. You may be experiencing a cycle crash, or there may be too much demand on your bioload. Prior to treating your water for chlorine and chloramines during a water change, test your tap or well water. If there are naturally occurring nitrates that register on your test paper, you will need a dechlorinator that also neutralizes naturally occurring nitrates. Goldfish that are in high nitrate water for long periods of time will adjust to the stress on their bodies, but they will not thrive and they can die very early deaths due to such stress. Goldfish that are introduced to high nitrate water that are not acclimated to such conditions can die quickly.

    Contributing Problems to Goldfish Death

    • Unsanitary water with high nitrates can cause bacterial infections, flux, itch, breathing problems and swim bladder issues in wide-bellied fancy goldfish varieties. All of these problems can cause a death in your goldfish. High nitrates can kill your goldfish if you are unable to lower the nitrates in a timely manner.