What Kind Of Water Do Goldfish Need?

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Imagine you have a pet fish in your aquarium. Which one is the first that comes to your mind? A goldfish, right? Goldfishes are perhaps the most common pet fishes that are seen now. This relatively small member of the carp family is native to East Asia and was first selectively breed in ancient China. Many distinct breeds have been developed since, and they vary in size, body shape, fin configuration, eye configuration, and coloration. The most common types of goldfishes are common goldfish, black moor, bubble eye, comet, fantail, lion-head, oranda, ryukin, shubunkin, etc.

To ensure the proper environment for your pet fish, the first question you should ask is, What kind of water do Goldfish need? This article is going to help you find an answer to this question.

How long do goldfish live?

The average life expectancy in an aquarium is five to ten years. In the wild, they can live up to twenty-five years. However, in captivity, their lifespan depends mostly on the care that the fish receives and the environment of the tank.

Is tap water safe for a goldfish?

I’ve been asked many times, “Can a goldfish live in tap water without a filter? as it reduces the maintenance cost greatly. Well, they can’t.

Regular tap water is disinfected with chlorine and chloramine. Upon disinfection, the water becomes safe for us to drink, but as chlorine in water causes damage to the gills of goldfishes, it becomes incredibly detrimental to goldfishes as they are less likely to thrive with damaged gills.
Tap water also contains heavy metals like zinc, cadmium, and lead. Though goldfishes need some heavy metals (such as zinc), heavy metals in high concentrations induce great stresses to the goldfishes.

What should be the pH of water in the tank?

Another essential factor to be considered is the pH of the water. For the proper health and growth of a goldfish, the pH of the water should be 7 to 8.4. Some fancy breeds are susceptible to the pH of water. The pH of tap water varies from area to area within a pH range of 6.5 to 8.5.

What should be the temperature of the water in the tank?

The growth of a goldfish in the aquarium is also dependent on the temperature of the water. Fancy goldfishes require a steady temperature of 68° to 74° F, whereas the optimum temperature for shubunkins and comets is 60° to 70°F. It is a great practice to vary the temperature of the water in the tank to mimic the temperature changes of their natural habitat during various seasons. If you’re looking for your goldfish to breed, the temperature of the water should be about 68°F.

The easiest way to maintain the temperature of the water is to use an aquarium heater. But in many areas, an aquarium heater is not needed if the fish tank is kept indoors as the temperature is less likely to fall outside of the safe range.

How often should you clean your tank?

Goldfishes produce an enormous amount of waste compared to other common pet fishes. The waste in the water is detrimental to the goldfish itself. I would suggest changing 10 percent of the water every week. You should change at least 25 percent of the water if you are cleaning every two weeks.
In the following context, we’ll be taking a walk through the water requirements for various types of goldfishes.

The Common Goldfish
The scientific name of the common goldfish is Carassius Auratus. The word Auratus comes from the Latin root aurat-, meaning “gold” or “golden” refers to the color of the fish. The common goldfish is related to carp, koi, and other types of breeds. It was the first breed and domesticated in ancient China and been one of the most common pet fish since then. It is fish that is well-suited for beginners as it is a very hardy breed. The optimum temperature of water for this fish ranges from 55°F to 80°F, and the pH of the water should be 6 to 8, which is much like tap water. It doesn’t need an aquarium heater and needs only minimal care if the water is well-filtered. The fish tank should contain about 10 gallons of water. They do very well in water with a temperature around the low 70s. A small one-gallon bowl is not recommended.



The comet goldfishes are thought to native to the state of Washington and were breeds in the late 1800s. It is similar to the common goldfish, but they’re slightly smaller and slimmer and is mainly distinguished by its long, deeply forked tail. It comes in many varieties, the most popular being metallic orange in color as the color shows well in fish ponds. The comet doesn’t require much-specialized care. It is generally playful and peaceful. It has an average lifespan of four to fifteen years. With proper care, it can grow up to 12 inches in length. It has an omnivorous dietary habit. The comet requires a minimum tank size of 50 gallons. Compared to the fancy goldfishes, a comet is a hardier breed. It is quite tolerant of a wide range of water temperatures. They can endure cold ponds all winter long. So, an aquarium heater is not a must, but they thrive the best in a temperature range of 65 to 70°F. Plants in the aquarium also impact the growth of the fish positively. Live plants provide shelter to the fish, and it feels safer.  The plants also provide a bit of food to the comet as comets being omnivorous.

Black Moor

Blackmoor is one of the hardiest breeds. As the name suggests, they’re black in color, have characteristic protruding eyes, and have round and stubby body shape, unlike the slim-bodied comet. They grow up to 8 inches and may live up to 20 years. Blackmoor is considered to be one of the best fishes to keep as a pet.

Being a hardy breed, they’re effortless to keep in a 10-gallon tank. They’re not very sensitive to extreme temperature changes and have an optimum temperature range of 65 to 72°F. They’re relatively tolerant of extreme temperatures, but rapid temperature changes shorten the lifespan. Installation of a thermostat-controlled heater to the aquarium ensures the temperature of the water remains constant and thus a safe environment for the fish. The pH of the water should be 6 to 8.

The water should be carefully dechlorinated by leaving the water in the container for 24 hours for the chlorine to dissipate or using a commercial dechlorinator.
Regular water changes are also necessary for proper growth, even with a filter installed in the tank. Twenty-five percent of the water should be removed and replace it with fresh, every week.


Bubble Eye

The bubble eye goldfish is very interesting due to their unique eye appearance. The eyes of this fish are forced upwards from pressure caused by the fluid sacs that develop underneath the eyes. This goldfish type was first originated in China. With proper care, a bubble eye goldfish grows up to 6 inches and may live up to 15 years. Bubble eye goldfishes are among the more delicate species of goldfish as their eye sacs are pretty sensitive.

The tank size should be at least 10-gallons. A 20-gallon tank is the best for a single bubble eye goldfish, and tank size should be increased by at least 10-gallons upon further addition of each bubble fish.

The optimum temperature range for bubble eye goldfish is 65 – 72° F (18°- 22° C). The flat-bodied types of goldfishes can tolerate low temperatures, whereas bubble eye goldfish cannot tolerate temperatures much below 60° F (16° C), and they do not like warmer temperatures either. The water should have a pH range between 7 to 7.6 and a water hardness of 5 to 19 kDH.
A quarter of the water should be replaced with fresh water to keep the ammonia and nitrate levels minimal.


Goldfishes have been kept as pet fishes for many centuries. This long time of domestication has led to the emergence of many greatly diverse breeds. Some of these breeds are very hardy in nature, and the more fancy ones are quite sensitive to the care they receive. The growth and survival of a goldfish depend very much on what kind of water do goldfish need and what type of water they actually get. The important parameters of the water are the temperature, the pH of the water, the cleanliness, the pH of the water. You must ensure that the water in your tank meets the requirement of your fish.

If you’re concerned about the health of your goldfish, I’d recommend you buy a solution for an aquarium that has chlorine and ammonia removed, and acidity neutralized. This type of solution is available at almost every pet store. To ensure an optimum environment, have an aquarium environment install a filter and a thermostat aquarium heater to your fish tank.



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