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What Kind of Water do Goldfish Need?

Goldfish are a type of ornamental carp and highly popular among freshwater aquarists. Easy to feed and care for with a gentle, sociable nature, this species does best in an extra-large indoor tank or outdoor pond environment. If you’re thinking of keeping goldfish, you may be wondering what kind of water they require?

Goldfish are cold water fish, so they don’t require a heater. They prefer fresh water that ranges in temperature between 62- and 72-degrees Fahrenheit. Water that’s higher in alkalinity (7.5) is okay but the ideal pH is closer to neutral (7.0 to 7.3). The recommended carbonate hardness is around 120ppm.

Now that you know the type of water goldfish need, let’s explore this topic together in more detail. We’ll learn what water parameters are best and how water conditions affect goldfish behavior. We’ll also discover if reverse osmosis or tap water is better for goldfish and how to properly treat the water. We’ll even explore the need for aquarium equipment such as filters and/or air pumps.

So, if you’re ready to learn more about goldfish and the aquatic conditions they need not just to survive but thrive in captivity, then let’s begin!

Do Goldfish Prefer Hard or Soft Water?

Goldfish prefer harder water, though they’re highly adaptable and can survive in somewhat softer water as well. Water with a neutral pH (7.0) is best however, a slightly more alkaline environment (up to 7.5) is okay too. The salinity of the water must be zero, meaning no presence of dissolved salt at all! The only minerals they need from their water is calcium and magnesium, which are found naturally in hard water.

What Water Temperature is Best for Goldfish?

Goldfish are a type of cold-water carp fish. The ideal temperature for fancy goldfish, for example, is between 68- and 74-degrees Fahrenheit. Ryukins like their water a bit cooler around 64- to 72-degrees Fahrenheit while shubunkins prefer their water cooler yet at 60- to 70-degrees Fahrenheit. Keeping the tank between 62- and 72- degrees Fahrenheit should be good for just about any species of goldfish.

What pH Level is Best for Goldfish?

Goldfish are a hardy species of freshwater fish and can adapt to a variety of water conditions. When it comes pH level, they can adjust to fluctuations between 7.0 and 7.5. That said, if the pH is too far off from this range, goldfish will start to show physical signs of stress such as lethargy, loss of appetite, and changes in coloration. To keep your fish healthy, invest in a pH test kit and analyze the water regularly.

gold goldfish

What Carbonate Hardness is Best for Goldfish?

Carbonate hardness is the amount of carbonate and bicarbonate found naturally in water. For goldfish, the optimum level is 120ppm (parts-per-million). These fish are both hardy and adaptable so they can adjust to a hardness level ranging from 80ppm to 160ppm. Since this species needs calcium for optimal health, test the hardness of the water regularly and if it’s too low, add some limestone to the aquarium.


Is Tap Water Good for Goldfish?

Tap water is best for goldfish. They need the minerals found naturally in the water (such as calcium and magnesium) for optimal health. That said, the water must be pre-treated with a dechlorinating agent like API Tap Water Conditioner (Amazon link) before introducing fish. A high concentration of chlorine in the water is dangerous for fish, causing respiratory problems and skin/gill damage.

Is RO Water Good for Goldfish?

While reverse osmosis water is okay for goldfish, it’s not necessary and they’ll do just fine in treated tap water. Using RO in an aquarium can be quite expensive and is mainly recommended for saltwater fish. You can, however, mix RO water with treated tap water for goldfish. This will help soften the water a bit as well as neutralize chlorine and other heavy metals.

Do Plants Make the Water Better for Goldfish?

Live plants in a goldfish tank help improve the quality of the water by oxygenating the environment and removing harmful compounds like ammonia and carbon dioxide. These fish are omnivorous, so live plants also act as a healthy, natural food source. The best plants for a goldfish aquarium include anubias, java fern, and water lettuce. Avoid toxic or flowering plants such as azalea, jasmine, or wisteria.

What Happens if You Put Goldfish in Saltwater?

Goldfish, though hardy and highly adaptable to a variety of water conditions, cannot survive for long in a saltwater environment. If you put this species in water with a salinity higher then zero, the fish will die. The only time they may tolerate brackish (mix of salt and fresh) water is in the wild and that’s just for a short time – to swim from one river to another.

How do You Prepare Water for Goldfish?

To make tap water safe for your goldfish tank, you must treat it in advance with a water conditioner or dechlorinating agent. This product will neutralize chlorine and chloramine while removing heavy metals from the water. After treating the water, it’s bet to wait at least 24 hours before adding goldfish to the aquarium. Better yet, do a water test the next day and if it’s safe, then introduce your fish to the tank.

Do Water Parameters Affect Goldfish Temperament?

Water parameters directly affect goldfish temperament. If the temperature or pH is ‘off’, goldfish will become anxious and possibly aggressive. As well, if there are high amounts of toxic compounds in the water such as ammonia, nitrates, and nitrites, goldfish can become stressed or ill which also affects their typically sociable behavior. They may act timid or shy around tankmates and hide out often.

Do Goldfish Need an Air Pump?

An air pump isn’t necessary in a goldfish tank, though it doesn’t hurt either. Air pumps help add oxygen to the water by creating surface agitation. Oxygen is vital for all living creatures, including fish. In my opinion, installing an air pump (and an air stone) will only benefit your pet goldfish in the long run by improving their overall health and quality of life.

goldfish swimming in bubbles


Can Goldfish Live without a Filter?

Goldfish are one of the few freshwater fish that can live without a filter in their tank. Though not required, I personally recommend that you install one. A filter will allow beneficial bacteria to grow, which improves water quality and helps keep the aquarium clean. If you don’t have a filter in your tank, then you must be prepared to do more water changes since goldfish are notoriously ‘messy’ fish.

Final Thoughts

To conclude, goldfish are cold, freshwater fish. They don’t require a heated aquatic environment and thrive in water that’s more alkaline than acidic. The recommended tank or pond temperature for this species is between 62- and 72-degrees Fahrenheit with a pH level of 7.0 to 7.3 and a carbonate hardness of 120ppm. Though hardy and adaptable, maintaining a stable aquatic environment will promote both longevity and health.

I hope this article has been of help to you and answered your all questions about goldfish and their preferred aquatic conditions. Thanks for reading and good luck with your aquarium hobby!

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