How Long Do Comet Goldfish Live? (Surprising Answer)

Yesterday I went to my friend’s house and he has a lot of comet goldfish in his aquarium.

I asked him how long do comet goldfish live and he didn’t have the answer.

So I did some research and find out that the average lifespan of comet goldfish is 5 to 14 years. 

Now, I know, these are pretty vague figures but the lifespan of comet goldfish is really depended upon the environment in which it lives.

And if you took good care of them it can leave more than 14 years.

How Long Do Comet Goldfish Live image

Full-grown Comet Goldfish

The full-grown comet goldfish is about 12 inches long and they live about 14 years. 

It requires a minimum 50-gallon tank for a single full-grown comet goldfish.

The yellow/orange color is very common in comet goldfish. But they also come in several other varieties like

  • Red and white
  • White
  • Brown
  • Black (It is a hybrid of Koi and comet goldfish)

What Factors Affect the Lifespan of Comet Goldfish

There are several factors that affect the lifespan of a comet goldfish.

Tank size

Tank size is probably the most important factor that can affect the lifespan of a comet goldfish. 

A single comet goldfish requires a large 50-gallon tank. If you can manage to get a 75-gallon tank then it is even better.

If you put them into small size aquarium then they will get stunt i.e. they will not grow up to their full potential.


The comet goldfish are the descendants of Prussian Carp. 

The Prussian Carp are omnivorous, so they eat both plant and animals.

The majority of their diet is vegetarian so you should feed them a lot of vegetables and also some non-vegetarian foods like flakes and pellets.

Just don’t feed them bread. It causes indigestion. If you run out of food then you’ll have sufficient time to get the food because goldfish can survive without food for a long time.

We usually see people feed bread to fish but it is not good for them and it causes indigestion.


Comet goldfish produces a lot of bio load so you should use a good filtration system in a comet goldfish tank.

You can use a powerful hang on the back filter or if you have a budget then go for a canister filter.


In there natural habitat, comet goldfish live in a cold water river.

So you should keep comet goldfish in cold water.

If the water gets to worm then it can potentially damage their nerves.


As comet goldfish require a lot of space if you keep other mates with your comet goldfish then you better put them into a large tank or else they might get stunt.

How to Care for Comet Goldfish to Maximize its Life Expectancy

How to Care for Comet Goldfish to Maximize its Life Expectancy infographic

The comet goldfish to reach its maximum lifespan you have to create an optimum environment for them in your aquarium.

Comet goldfish are very hardy fish. The average lifespan of a comet goldfish is 4 to 14 years. And if you took good care of them then they can live even longer.

I am going to share with you some tips to increase lifespan of your comet goldfish.

Tank Size

Ideally, you should keep your comet goldfish in a pond because they require a lot of space.

But if you want to keep them into the tank then the tank should be a minimum 50 gallons for each comet goldfish.

If you can manage to get up to 75 gallon then it is even better.

Also, make sure that the tank is of rectangular shape so the comet goldfish will get a lot of space to swim.


Comet goldfish is omnivorous so they eat both plants and animals.

To fulfill their vegetarian diet you can feed them vegetarian flakes and pellets.

You should also place some live plants into their tank. 

These live plants are very good food for them and they also help to increase oxygen in the tank.

You can also feed them other human foods like:

  • Carrot
  • Spinach
  • Apple
  • Oranges
  • Broccoli
  • Lettuce

To fulfill the non-vegetarian diet of comet goldfish you can feed them non-vegetarian flakes and pellets.

Besides you can also feed them small insects, worms, etc.

Ideally, you should feed them 2 to 3 times a day. It is very easy to overfeed a fish so you should feed them the amount of food they can consume within 2 minutes.

Or feeding them food equals to the size of their eye is a good rule of thumb.


In their natural habitat comet goldfish live in a cold water river.

Basically, all species of goldfish require cold water.

So you should keep them in a cold water aquarium of about 50 to 75 degrees Fahrenheit.

Also, make sure that the aquarium is not near any heat source or near the window because the sun rays coming from the window may increase the water temperature of the tank.

If the water gets to warm then it can cause lifelong damage to their nerves.

The pH of the water should be between 6.5 and 7.5.


As I mentioned above comet goldfish require a lot of space about 50 gallons per fish.

So if you are planning to introduce a mate for your comet goldfish then you should put them into a large tank.

Usually, comet goldfish are not aggressive but they get aggressive when you feed them so there are chances that other fishes may get malnourished.

But there are some good mates for comet goldfish.

You can keep other types of goldfish and Koi with your comet goldfish.

Other good Mats for your comet goldfish are:

  • Zebra danios
  • Weather loaches
  • Rosy barbs
  • Bristlenose plecos


So comet goldfish can live about 4-14 years and if they live in an optimum environment then they can live even longer.

There are various factors that affect the lifespan of the comet goldfish like the size of the tank. The comet goldfish requires a lot of space so you should keep it in a minimum 50-gallon tank.

Also, you should feed them both vagitarian and non-vegetarian diets for their optimum growth.

Comet goldfish produces a lot of bio-load so you should have a good filtration in place.


How can you tell if a comet goldfish is male or female?

There are several ways to identify a male and female goldfish
Female comet goldfish have rounder and thicker body shape and male comet goldfish have a longer and thinner body shape

Protruding vent
The female comet goldfish have rounder protruding vent than the males.

The simplest way to know if your comet goldfish fish is male is by looking at the tubercles which are white spots on their gills’ shield.

Shape and length of fins
The pectoral fins of male goldfish is usually longer, thinner and pointed than the female goldfish.
The pectoral fins of female goldfish are shorter and around.

Chasing behavior
Changing behavior is considered as the most reliable way to know if a fish is male or female.
During spawning season male goldfish will chase the female goldfish.
But if the tank contains only male fish then the male fish may also chase each other.
So using the other methods like the physical differences as well as the chasing behavior is a good way to know if a goldfish is male or female.

Do comet goldfish eat other fish?

Comet Goldfish is not usually aggressive. But they get aggressive when it comes to feeding.
Usually, comet Goldfish will not eat other fish if they are bigger in size.
But comet Goldfish can eat smaller fish like guppies and even their own baby Goldfish.
They also eat their own eggs.

Do comet Goldfish need a heater?

Comet Goldfish is a cold-water fish so usually does not require a heater.
They can tolerate low water temperatures pretty easily. But if the water temperature rises then it can be harmful to their nerves.
So during the hot days to keep the water temperature low you can put a table fan near the tank that will blow over the top of the water or you can use a cooling fan specially designed for aquariums.

Do comet Goldfish need an air pump?

Comet Goldfish is a very active fish and it requires a lot of oxygen to carry out its activities.
Comet Goldfish take oxygen through their mouth and then it went into an organ called rake where the dissolved oxygen gets absorbed into the bloodstream which is later provided to other organs of the body that helps to function them properly.
Later the carbon dioxide is excreted out through their gills.
Though there are a lot of ways to increase oxygen in the aquarium but an air pump is the most reliable and simple way to oxygenate any fish tank.
There are several signs that can tell you if your Comet Goldfish aquarium needs air pump or not.
1. Does your Comet Goldfish come on the surface gasping for air frequently? It is their natural behavior to come on the surface to gulp some air but it is very infrequent.
2. Did you notice the fast movement of the gills of your Comet Goldfish? It is a strong sign that they are not getting enough oxygen.
3. Is your Comet Goldfish moving slowly? This may be because your your fish tank is not well oxygenated.
If you noticed any of the above signs then you will be required to install an air pump in your tank.

Photo of author
Prathmesh Gawai
He is the main author and editor at And he loves to share helpful information on aquarium and/or fishkeeping hobby. Prathmesh has over five years of aquarium and/or fishkeeping experience. Currently, he has a Betta fish tank. He has written hundreds of articles on various aquarium fish species and on fish tank maintenance over the last five years. Connect with him on YouTube here. Learn more about him here.

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