There are a lot of known varieties of Goldfish, and the Comet Goldfish is one of the most popular ones. Aquarium owners love to have them in their tanks because they are one of the most beautiful fish species. The scientific name of the Goldfish species is Carassius auratus. The original goldfish were native to East Asia and they were selectively bred to get different subspecies and variants of personal choices. For example, some people perfected the coloring of goldfish, while some worked on making them durable, and increased their lifespan. The Comet Goldfish is one of the rare varieties that are not only beautiful but also last longer.

This fish species is known for its beautiful appearance and peaceful nature. Also, this is one of the most durable fish species, and it can live in your tank for more than ten years if you properly take care of it. You can also pair them with a variety of other fish types and species, which means they are compatible with community aquariums. The article below contains complete information about taking care of the Comet Goldfish.

Basic Facts Table

LifespanUp to 4 years with minimal care but up to 14 years with excellent care.
Size4 inches average, 12 inches maximum.
ColorsYellow, orange, white, red
Freshwater or Saltwaterfreshwater
Care LevelMinimum for short lifespan, expert-level for a long and healthy lifespan.
CompatibilityPeaceful community tanks

Tank Companions

To find the perfect pair for the Comet Goldfish, you need to know a few things about the Comet Goldfish and match these requirements with the potential candidates. This will help you find the most suitable tank partners for the Comet Goldfish. The first thing that you need to know is that the Comet Goldfish has a specific range of parameters inside the aquarium. So, any fish species that you want to pair with the Comet Goldfish, must have similar parameters or must be able to live in similar parameters.

If you don’t check that, there is a chance that you might select the wrong species of fish that would die as soon as you put it inside the aquarium with Comet Goldfish parameters. For better understanding, you can consider this example, the Comet Goldfish lives in the freshwater aquariums, with moderately warm water. So, if you paired them with a species of fish that lives in cold waters or the one that lives in the brackish or saltwater, it would die within a few days.

The second most important thing to check in a possible pair of the Comet Goldfish is the nature of that fish. The Comet Goldfish is a passive-aggressive fish species. Meaning that they remain peaceful for most of the time. But if they are threatened or attacked, they would retaliate instead of running and hiding. So, introducing them to the aggressive fish species would be a mistake because they would fight and your fish would be under stress most of the time. So, make sure that your fish has a similar peaceful nature as the Comet Goldfish.

The third most important thing is the size of the fish that you want to introduce in the tank of Comet Goldfish. As you know, healthy Comet Goldfish can grow up to 12 inches and more. So, if you introduced them to smaller species that are only one or two inches large, the Comet Goldfish would consider them food and would eat them. So, make sure that you add only those fish species that have similar size as the Comet Goldfish inside your tank. Here is a list of the possible candidates for the Comet Goldfish tank mates.

  • Rosy Barbs
  • Weather Loaches
  • Zebra Danios
  • Bristlenose Plecos
  • Shubunkin
  • Black Skirt Tetras
  • Wakin Goldfish
  • Jikin Goldfish
  • Dojo Loaches
  • Koi Fish
  • Guppies

All of these are the best potential candidates for the tank of Comet Goldfish because most of them have similar nature, size, and can live in similar tank conditions/parameters.

Species Overview

The Comet Goldfish is a variety/breed of goldfish species from the Cyprinidae family. It is one of those fish variants that can live long in your tank if you provide them with proper care. Also, it is one of the most popular variants of the goldfish that has been present in aquariums since the 1800s. The Comet Goldfish was selectively bred to perfect the color pattern but it also helped them become hardy to most of the adverse conditions. That is why this fish has become so popular because not only is it beautiful, it lasts longer as compared to most other aquarium fish species that only last a few years.

Also, this selective breeding helped them become a dominant species. Because this variety has developed a different type of breeding system that allows them to breed more successfully and produce more offspring. Its care guidelines are similar to most other goldfish species. So, if you are properly taking care of them, you can hope for a lifespan of 10 years or more. Some Comet Goldfish have been known to live more than 20 years in captivity. As they age, the size of the fish also increases. That is why there is a wide range of sizes when it comes to finding a Comet Goldfish. You will notice that a lot of them are four to five inches long but there are also a lot of individuals that are more than 12 inches long.


The appearance of the Comet Goldfish is similar to other varieties of the goldfish. It has the same type of body shape. But it has distinct color patterns, fins, and slight variations in the shape of its body. This fish is called Comet Goldfish because it is shaped like a comet. Most of the other goldfish have a stiff and small tail but the Comet Goldfish has a long tail. Also, the tail of the Comet Goldfish is transparent towards the edges. The golden color in its body fades towards the edges of the fins and they become transparent. The Comet Goldfish has a white underbelly.

As they have long tail fins, they help them swim faster and coordinate their movements better in the water as they swim. Its tail is shaped like a fork. It has large dorsal fins and anal fins. Similar to the tail fin, these fins are also partially transparent. There are multiple colors and sizes available in the market. So, you can pick the color and size of your choice when it comes to the Comet Goldfish. Red, orange, golden, white, and black are some of the most popular color choices when it comes to Comet Goldfish. There are also some spotted versions of the Comet Goldfish that are available in the market. These spotted varieties have multiple colors.

The average size of this fish depends on the care that you provide or the conditions in which this fish is being kept. For example, if you are properly taking care of this fish and it has a large tank to swim in and explore. It can grow up to 14 inches long. But if your tank conditions are not suitable for the Comet Goldfish, they would only grow up to 4 to 5 inches. So, you will need to make sure that you provide them with the perfect conditions so that they can reach their maximum size.


The Comet Goldfish is a variety of goldfish that was selectively bred. It was bred in the United States by Hugo Mulertt in the 1880s. Since then it has become one of the most popular goldfish breeds in the world. This fish variety has a lot of advantages over the other goldfish, for example, an extended lifespan, more durability, and the ability to resist changes in the water.

The original Comet Goldfish had orange-gold color but since then, there have been a lot of genetic mutations that helped develop specific colors such as black, golden, red, and spotted Comet Goldfish. The goldfish were native to East Asia. They were common pond fish in Japan and China. Most of the work on selective breeding of the goldfish started there and these more colorful variants were developed using similar breeding techniques.

Natural Habitat

This fish species is not found in natural habitats. But the original goldfish (its predecessors) had a natural habitat. As they originate from the goldfish, we would consider the habitat of goldfish as the habitat of the Comet Goldfish. The habitat of the goldfish has large plants, soft bedding with stones and sand, and it has a large area for them to explore. Apart from that, this natural habitat contains small invertebrates, insects, and larvae that this fish uses as a food source.

Comet Goldfish Lifespan

As I have mentioned earlier, Comet Goldfish is one of those fish species where the lifespan depends on the type of care that you are providing. So, if you are providing excellent care, your fish can live for more than 14 years. Some are even known to have lived for more than 20 years because the conditions were kept perfect throughout their lifespan. But, if your care is not excellent, but mediocre, your fish could live up to 10 years. This lifespan will be even shorter if you are providing them minimal care. So, if you want your fish to live long and stay healthy in your tank, make sure to provide them with the excellent conditions that they need. The guide below will help you expand the lifespan of your Comet Goldfish.

Habitat and Tank Conditions

If you want your fish to stay healthy and have a long lifespan, you will have to create a perfect habitat for them. You can do this by making the right choices when it comes to the size, setup, decorations, tank companions, number of fish, and water parameters. You need to know all of these things before creating a tank and putting your fish inside that tank. Here is a complete guide related to building a perfect tank for your Comet Goldfish.

Tank Size

The first thing that you need to know when you are creating a habitat for your fish is the size of the tank that you need. A lot of people keep the Comet Goldfish in outdoor ponds but you can also keep them in a tank or aquarium. If you want to keep them in an aquarium or tank, you will need to select a tank that is large enough to accommodate your population of the Comet Goldfish. There are three main factors when it comes to the size of the tank.

First, you know the number of Comet Goldfish you will put in the tank. Second, you need to know the fish per gallon ratio of the Comet Goldfish (according to the size of the fish). Third, you need to make sure that your tank has enough space for additional fish or when your fish grow (in size). For example, if you are making a tank when your fish are only 2 to 3 inches long, you should keep in mind that with proper care they can grow up to 12 inches. So make sure that your tank is large enough to accommodate all of your fish.

When it comes to Comet Goldfish’s ideal tank size, the formula is simple: the bigger the number of your fish, the bigger the tank you should select. The minimum size of the tank that you can use for keeping a population of the Comet Goldfish is 50 gallons. But if you can buy any bigger tank, or create a special tank that is larger than this capacity, you should go for that size. A 75 gallons capacity tank is the recommended size of the Comet Goldfish.

Tank Setup

After selecting the tank of the right size, you will have to start working on creating a habitat inside that tank. A tank setup refers to the tank environment that you create for your fish inside the tank. For example, you plant some vegetation in your tank, add a substrate, spread some stones, and add some decorations inside your tank. When you are starting to work on your tank setup, you should start from the bottom layer. Add a soft treated sand layer, and a fine-grained substrate or gravel. After that, you can add stones to the bottom layer of your tank. Once you are done with that, you should add some aquatic plants inside your tank.

Aquatic plants and decorations that you will add to your tank will make it look more natural. You can also put decorations and caves for the Comet Goldfish to explore. You will also have to add a filtration system inside your tank. It is important to select a larger and more powerful filtration system for the tank of Comet Goldfish. It will keep the water clean, provide oxygen, and will produce wave current or flow inside the tank. You will also have to add a heater or temperature monitoring, a controlling device for your tank. It will allow you to maintain the same temperature in your aquarium. Apart from all of this, you will also have to add some lights to your tank. You should use standard aquarium lights for this purpose.

Water Conditions/Parameters

Apart from creating a perfect habitat or environment inside the tank, you will also have to monitor and maintain certain parameters inside your tank to keep your Comet Goldfish healthy. The important parameters include water temperature, pH, and hardness. Below are the recommended ranges of these three parameters that are suitable for the health of Comet Goldfish.

  • Temperature between 50 to 75°F
  • pH levels between 6.5 to 7.5
  • Hardness between 5 to 20 dGH

It is very important to strictly maintain and monitor these parameters. Because any change in these parameters directly impacts the quality of life and the health of your Comet Goldfish. For example, changes in water temperature can cause the death of your Comet Goldfish as their internal temperature is directly controlled by the temperature of the water. So, it rises more than these limits, it can kill your fish. If you live in a cold region, you will have to use a water heater to maintain these temperatures.

Water Source

For the tank of Comet Goldfish, you can use water from any source. You can use the water of your tap, a local river, pond, or lake. But before adding this water to the tank, you will have to test it and clean it properly. There are standard cleaning methods that you can use or you can get reverse osmosis filtered water for your tanks. The quality of the water in your tank will determine the health, and lifespan of your fish, so you should spend some time making sure that you use the right type of water from the right type of source.

Behavior and Temperament

This fish is known for being passive-aggressive. Meaning that most of the time, it is peaceful, but if it is attacked or intimidated, it would fight back instead of running and hiding. It is very uncommon that they attack the other small fish in their tank but you should be careful and not pair them with smaller fish species. Because there is a chance that the Comet Goldfish would consider these smaller fish species as a food source. In that case, it would bully them, or even kill and eat them if the fish are too small.

It is a hyperactive fish that you can buy for your tank and enjoy watching. Comet Goldfish are known for their curiosity because you will see them exploring your entire tank. They will visit the caves that you placed inside the tank or any other decoration. According to many fish keepers, this is an intelligent fish and it remembers the owners and its surroundings. So, you should often change the decorations inside your tank to keep them interested in exploring your tank.

Breeding Comet Goldfish

Comet Goldfish is one of those fish species that are hard to breed if you are not an expert breeder. It needs specific conditions to breed that are difficult to replicate. Apart from that, they need a large space to breed. That is why keeping them in a pond is considered better because it provides them more space to breed. To successfully breed the Comet Goldfish, you will need a large tank that allows the pairs to swim and explore together before spawning and breeding.

You should create a very large tank to breed different species of goldfish and use it to breed the Comet Goldfish. Put some males and females in that tank, and start decreasing the temperature of the water inside the tank. As the water temperature lowers, it triggers a breeding and spawning response in the Comet Goldfish. Keep gradually decreasing the temperature for a month and when you reach 58°F, you should gradually increase the temperature over the next month until you reach 70°F. It would create a similar condition in which other fish of this species spawn in nature.

You will also have to increase the amount of diet for them. Because female Comet Goldfish would need more food to produce eggs. It produces more than 1000 eggs and disposes them inside the tank. The male Comet Goldfish would fertilize these eggs. After that, these eggs will need a few days to hatch and become Fry. 

Eggs and Fry Care

It is better to remove both males and females from the breeding and tank and allow the eggs to hatch. It will take a few days but the eggs will hatch and small Fry will come out of these eggs. This Fry would eat the egg sacs that they were in and after that, they would need food from you. There is special food available for the Fry that you can buy and feed them. Keep them inside this tank for some time and once they reach a significant size, you can reintroduce them to their parents’ tank. If there are changes in water conditions or parameters or if there are cleaning and filtration issues in the breeding tank, the Fry would die before reaching maturity. So, you will have to be extra careful.

Diet of Comet Goldfish

The diet of Comet Goldfish is an omnivore, similar to other goldfish. You can feed them pellet food, flakes, and live invertebrates such as small insects, worms, bloodworms, and mosquito larvae. Apart from that, there are specialized diets for this fish species that you can buy and feed them. These fish diets are made after a lot of research, and they contain everything that your Comet Goldfish will need. Apart from the meat-based diet, the Comet Goldfish also eats small vegetables that are chopped and spread in the tank or pond. You will have to feed them two to three times a day.

Diseases of Comet Goldfish

There are a lot of diseases that you will have to look for in the population of your Comet Goldfish. If you see any signs of any disease, you should quarantine that individual, and clean your tank. There are fish treatments and medicines that are available for treating the diseases that attack Comet Goldfish. Here is a list of the possible diseases in the Comet Goldfish.

  • Goldfish Ich: Ich is one of the most common parasitic diseases found in the Comet Goldfish tanks. It causes white spots to form on the fish’s body. It is a treatable illness but requires quarantine, cleaning of tanks, and other measures to prevent an outbreak.
  • Swim Bladder Disease: It is also a common fish disease that is identified by the bloating of fish. This happens because of bladder infections that are caused by bacteria in water. This can also spread that is why quarantine and treatment using medicine are recommended.
  • Fin Rot: Fin Rot is very common in the aging Comet Goldfish. It happens for several reasons and can be prevented by maintaining the quality of water and a peaceful environment.

What is the Ideal Size For The Tank?

The smallest tank that you can use for the Comet Goldfish is a 50 gallons capacity tank, but this is not a recommended tank size or the ideal tank size. The ideal tank size for the Comet Goldfish starts after 75 gallons or more. You should buy a large tank because the Comet Goldfish need a large space to grow in size and live longer. It is one of the basic requirements that help them age better and become healthier. A lot of people also use small ponds for keeping the Comet Goldfish instead of tanks. If you have a pond where you can maintain the parameters, you should use that for keeping your Comet Goldfish population.

Are Comet Gold Fishes Saltwater or Freshwater Species?

Comet Goldfish is a freshwater fish species. They are a variety of goldfish that live in freshwater aquariums. It is not found in natural environments because it is one of those fish species that were created using selective breeding. It lives in the freshwater aquariums. 

Are Comet Gold Fishes schooling species or not?

Yes, it is a schooling fish species. But to see this type of behavior from your Comet Goldfish, you will have to put more than 5 in the same tank. They like swimming in swarms or groups which is known as schooling or shoaling.

Conclusion – Are Comet Gold Fishes Suitable For Your Aquarium?

Comet Goldfish are suitable for anyone’s aquarium who can take care of goldfish species. This fish needs more attention and requires more care, that is why it might not be suitable for the new fishkeepers. It is one of the most beautiful, and hyperactive fish species that loves to explore. If you put more than 5 in the same tank, you will be able to witness their schooling behavior. You can keep them in a community tank with other goldfish or fish from other species. It is one of the best and most popular choices for those who love the goldfish and want to keep seeing them in their tanks.


Question: What is the size of a full-grown Comet Goldfish?

Answer: The size of a full-grown comet goldfish can range from 4 to 12 inches. If you provide them excellent care, they would reach 12 inches in length but in poor conditions, they only grow up to 4 inches long.

Question: How to differentiate Comet Goldfish male and female?

Answer: Male Comet Goldfish are slim and angular, meanwhile the females are thicker and round. During the breeding season, this difference becomes more apparent.

Question: Are Comet Goldfish aggressive?

Answer: Comet Goldfish are known for being playful, and peaceful. They rarely show aggressive behavior.

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