Comet Goldfish – A Complete Guide (Care, Diet, Facts)

The Comet Goldfish is one of the most popular breeds of Goldfish today. First discovered in the mid 1800’s these Goldfish made its mark. Captivating enthusiasts all over from then to this very day.

The beauty of its vibrancy and long flowing tail are some of the main reasons for its attraction.  These Goldfish haven’t been beloved all these years for nothing.



The Comet Goldfish was given the scientific name of Carassius Auratus Auratus. This specific breed is not a natural breed to the wild. It is a branch off the Prussian Carps. Hugo Mulertt founded with breed when he was working on a selective breeding program.

Since the initial breeding in the 1800’s a love for the Comet Goldfish has developed and not slowed down. Hobbyist everywhere have wanted this Goldfish in their tanks for centuries, with no sign of digression.

They gained this love due to their vibrant colors and their durability. A Comet that is well fed and maintained can live up to 14 years old. With the right food and tank conditions the Comet can grow up to 12 inches long.

When first breed these fish were an orange or yellow hue. Although, due to further selective breeding they can now be found in a wider variety of colors.

Behavior Patterns

This fish is an overly active fish with a fun personality. Adding lots of movement and entertainment throughout your fish tank. They are speedy swimmers and spend most of their time their marking out their surroundings.

Some people even say that this fish is smart enough to remember their owners; along with their tank decorations. People believe that if you change up or move the decorations every month or so it adds excitement and fun for your fish to relearn everything.

The Comet Goldfish can become rather aggressive during feedings. This can be limited by feeding a cross the whole tank rather than in one small area. Doing this will cause less competition in a small area.


The Comet Goldfish is most vastly recognized by its glowing tail. The tail resembles comet more or less; hints the name. The common Goldfish has fins of even length, that don’t flow rather a stiff fin. As well as the common Goldfish is larger in size than the Comet.

You may not be able to make out the two fish by just looking at the size of the fish. The biggest differences that you can use to differentiate between the two fish are the Comet Goldfish has a long overly forked tail, a thin body, a tail fin, and they only have a single anal fin. While regular Goldfish have two anal fins.

To ensure your fish is healthy ensure that the eyes are flat and not bulging out. That the scales are smooth and not bumping out along the body. And that it is a healthy size.

As mentioned before there used to be color variation of yellow/ orange. Although, due to selective breeding you can now find them in colors such as orange/red, red/white (often called a Sarasa Comet), white, brown, solid yellow, and black (this is a hybrid of a Koi/Comet Goldfish). You may also find a Comet that has a variation of white that is almost like a cloud color to it. Although these fish are called Shubunkin Goldfish.

Habitat and Tank Conditions

Keep in mind that these Goldfish were created in the 18th century. They were created by Hugo Mullert due to selective breeding on the wild caught Prussian Carp.

With that being said, it’s important to base your aquarium on the wild Prussian Carp because this is a stem off that wild fish. These Carp are native to Asia and lived-in slow-moving freshwater areas such as lakes and run-offs.

They also could be found in large ponds and ditches if they had enough water for these fish to happily swim around.

So, what about my tank?

More often than not you have you mind made up beforehand if you’re doing a tank or you’re going to go with a pond of some sort. This will tell you the amount of Comet Goldfish you may keep in said enclosure. If you are going to have 3 or less, you may keep them together in a ranked environment. Anything over 4 you should have a pond.

The most important feature to both pond and tank is that they have enough water lengthwise to provide plenty of space for the fish to swim freely. Being mid-level active fish, they need plenty area with mid-level waters to roam about.

When deciding on which type of substrate to use its recommended you use some sort of fine substrate like small gravel. It’s important you have some sort of plant life in your tank/pond to oxygenate the water. They will also use the plant life to hide in to feel safe and secure. You may use other decoration that the fish can use as hiding although it’s not necessary. You may notice your Comet Goldfish taking an occasional bite on your plant from time to time. This is normal behavior.

Tank Conditions

Unlike many breeds of fish these fish are cold water fish. You need to ensure you have no heating source on the tank and it’s kept in a cool room. If these fish are exposed to high heat their nerves will begin to die; this can be fatal.

This fish needs water that stays between 50°F and 75°F. This means that in a house you should never need any source of heating or cooling device. As most houses stay between these temperature measurements.

You should keep the Ph between 6.5 and 7.5. Comet Goldfish do not have a set water hardness that they need in order to survive. They are capable of living in both hard and soft waters.

You cannot over filter a tank of Comet Goldfish. The number one problem hobbyist come to is the fact that Goldfish as a species release a lot of bio-load which is toxic and can impact your tanks water quickly.

You should purchase a good filtration system within your budget. While keeping a weekly 25% water change. This means you replace ¼ of the water every week.

Fact or Legend?  Goldfish Grow to The Size of Their Tank?

Not True. Your local pet store may say that your Goldfish will grow to the size of its environment although this is very false. It is very bad and unhealthy to place a Comet Goldfish in a tank that is too small.

They need at least a 50-gallon tank per Comet Goldfish. Even 50 gives the Goldfish a tight space, we say they need at least 75 gallons.

You may have a smaller tank for juveniles although you will have to grow tank sizes as the fish mature.

Tank Mates

Although, this breed is nonaggressive they do not make good tank mates with very many fish. This isn’t anything to do with their personality.

The number one reason Comets don’t make good community members is because of their water condition. As they are tropical fish, they are one of the few cold-water tropical fish. Making them the outlier.

The other reasoning is because these fish are heavy eaters. They do tend to become aggressive during feeding and it’s hard to ensure that other fish within a tank of Comet Goldfish are not being malnourished.

For that fact these fish are best with other variations of Goldfish and Koi. It’s best if they are all around the same size full grown.

Although, if you want something different within you tank it is possible. Just ensure they have peaceful temperaments and are roughly the same size.

Keep in mind if you are mixing other fish to ensure they are eating at every feeding. Also make sure to find a happy medium with the water conditions.

Can You Keep Multiple Comet Goldfish in One Tank?

Of course, you can, as long as you have a large enough tank for them. You need at least 50 gallons per fish.


When deciding the exact diet these fish need in order to remain healthy, it’s important to look at their defendants. If you remember from earlier, they derived from the Prussian Carp. So, in order to fully understand what your Comet Goldfish needs for a wholesome diet let’s look at the Prussian Carp diet.

The Prussian Carp is an omnivore. Meaning it eats both meat and vegetables. In the wild they will feed on anything from plants, insects, algae, and even smaller fish. Although their main source of food comes from plant-based substances. They eat plenty of plants to get their fiber intake.

You may start out feeding your Comet fish flake or pellets that are specifically made for Goldfish. This will mean they were specially made for the fish to inhibit their exact supplement necessities and remain healthy. Although being engineered they often don’t stay in the fish’s system completely and you should not solely rely on these as their food source.

In order for your fish to be vibrant and have a great color potency throughout the tank, it’s important they receive their daily protein. You can do this by feeding them things such as insects, worms, bloodworms, or larvae.

Along with plants and vegetables that give them vitamins they need such as mashed peas, cucumbers, algae, carrots, zucchini, lettuce, broccoli, and some forms of sliced fruit.

Many hobbyists have a problem knowing when the fish has had enough to eat due to their natural instinct to keep eating until they have no food left.

A good rule of thumb to follow is to feed your Comet Goldfish 2-3 times a day for two minutes. Meaning place the food in and set a timer for two minutes, they will constantly eat for those two minutes and once the two minutes is up pull out the access food.

These fish have a major problem with bloating from eating too much. They will eat until they die if not stopped for it’s important to have a scheduled where they are not given that opportunity.

If water drops below 50°F Comet Goldfish begin to get digestive problems below that temperature. Allowing these fish to get to cold may become fatal.

Frequently Asked Questions!

What Is the Growth Rate for Comet Goldfish?

After hatching the Fish will grow up to 50% the first couple weeks. Slowing down after that taking 3 to 4 years to reach its fully matured size.

How Big Will They Get?

As mentioned before in my article a fully matured Comet Goldfish will get roughly 12 inches long. This is smaller than most other types of Goldfish.

What Is the Average Lifespan of The Comet Goldfish?

They may live between 4-14 years. This is a wide spectrum due to the number of factors that play into it. Between tank and food conditions and common illnesses that Comet Goldfish may get.

Illnesses such as Ich, flukes, anchor worms, fish live and etc..

What About Common Health Conditions?

As mentioned before Goldfish are prone to many health conditions and illnesses. These health conditions can be very detrimental to your Goldfish or the whole community. Things such as fin rot, fungal infections, and swim bladder disease.


I hope this guide provides you with some insight and answered any questions you may have about this specific breed of fish.

These fish are all around a great pick me up to add to any tank. As they are very vibrant colored fish and very active, outgoing, and young hearted fish. They make a great addition to a tank that is sought out for an entertaining addition.

As juveniles they may trick you due to being roughly two inches long. Although, they quickly become rather large and outgrow tanks less than 50 gallons.

These fish aren’t demanding but due to the size of tank needed for their large size they often won’t be found in the hands of a beginner.

These fish are cold water tropical fish making them hard to find tank makes. Although, it’s not impossible. You may just have to find that happy medium between the twos acceptable water temperatures.


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