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Can Goldfish Live In Brackish Water? We’ve Got The Answer!

goldfish in planted aquarium

Goldfish are naturally freshwater fish and thrive best in an environment with a low salinity content in the water. However, a goldfish can survive in brackish water conditions but only if the salinity content does not exceed 8 ppt.

Very few goldfish keepers will recommend keeping goldfish in an environment that has a lot of salt in it simply because a goldfish’s anatomy was not designed to function properly in water with a high concentration of salt. Aquarium salt is also a popular natural remedy for sick goldfish, but it should be used sparingly and only when necessary.

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What Is Brackish Aquarium Water?

A brackish aquarium consists of a mixture of fresh and salty water and is distinctly different in comparison to seawater. The term ‘brackish’ refers to the aquarium waters’ salinity content and it is the middle ground between marine and freshwater. The salinity content of the water for brackish aquariums is usually around 1.005 and 1.012 but the results can vary depending on the pH level of the water.

There are many species of fish that can tolerate and thrive well in a brackish aquarium; however, goldfish do not make the list.

Aquarium light
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Can Goldfish Live In Salty Water?

A goldfish’s ideal environment would consist of freshwater which can come from your household tap, bottled water, or a mixture of tap water and demineralized water. These types of water do not contain much salt and the salinity content is very low or sometimes not even traceable.

Goldfish can survive in saltwater for a short period, but it will not be good for them simply because their body and organs are not designed to live in high concentrations of salt. This makes goldfish unable to live in brackish water because of their physiological adaptation. Goldfish require less salt to maintain osmotic pressure than other fish which have adapted to living in brackish or marine conditions.

During this bodily osmotic process, goldfish will discharge water from their body to regulate a state of equilibrium. These body organs include the kidneys, liver, and intestines. The main organ affected by high concentrations of salt will be a goldfish’s kidneys because this organ helps to flush out waste and ions.

A sudden increase in the salinity of the water in a goldfish’s habitat will place a lot of unnecessary stress on their bodies as their organs have not adapted to processing large amounts of salts. This means that your goldfish will exert more energy to stabilize the way their body functions to stabilize organ functions in this new environment.

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Carassius auratus Goldfish
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How Long Can A Goldfish Live In Brackish Water For?

The length of time that a goldfish can survive in brackish water will depend on how much salt has been added to the aquarium. In some instances, when a slight increase of salt is added to your goldfish’s home, they may be able to adapt and not be affected by a low salinity content. However, if large amounts of salt are added to your goldfish aquarium, it can put their organs in distress and make them work extra hard to function properly. This stress can often be fatal to goldfish, and they could pass away.

Since a brackish aquarium is not the ideal environment for a goldfish, it could reduce their lifespan because the effects of high concentrations of salt in their bodies can cause their organs to over-exert themselves.

There are some cases where goldfish have adapted to low traces of salt in an aquarium with no problems, but the only issue was that once their bodies adapted to the new saline environment, the removal or reduction of salt from the water changed the way their organs functioned because their bodies got used to a certain level of salt.

Goldfish tank with gravel substrate
Image Credit: Hineck, Pixabay

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Final Thoughts

It is best to stick to keeping your goldfish in a freshwater environment that they have adapted to live in. It is not necessary to create a brackish environment for goldfish and may cause more harm than good if you are seeking to use salt as a form of antifungal or antibacterial in the water.

Salt should be used sparingly with goldfish in low quantities, and you should avoid adding it to the main aquarium if you plan to use brackish water conditions to treat an illness in your goldfish.


Featured Image Credit: Decha Photography, Shutterstock

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