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HomeFreshwater FishComet Goldfish: Size, Lifespan, Care & Tank Mates

Comet Goldfish: Size, Lifespan, Care & Tank Mates

Comet Goldfish have long been popular in the world of aquariums due to their captivating beauty and unique behaviors. However, owning these fish requires a significant amount of knowledge and preparation. There are various challenges that need to be addressed when it comes to Comet Goldfish care.

To assist you in this endeavor, DrywashAquarium have prepared a comprehensive guide on caring for Comet Goldfish. This guide will provide you with valuable information about their lifespan and how you can influence it, their size, tank requirements, diet, and other essential aspects of their care. By following this guide, you will be well-equipped to provide optimal care for your Comet Goldfish.

Comet Goldfish Facts & Overview

Information  Details 
Species Name  Carassius auratus 
Family  Cyprinidae 
Care Level  Easy 
Temperature  65°–72° Fahrenheit (18°–22°C) 
Temperament  Social 
Color Form  Yellow, orange, white, red 
Lifespan  5–14 years 
Size  4–12 inches (10–30 cm) 
Diet  Omnivore 
Minimum Tank Size  50 gallons (approximately 189 liters) 
Tank Set-Up  Freshwater 
Compatibility  Other fish that can’t fit in a Comet’s mouth and can handle lower water temperatures 

The Comet Goldfish, with its charismatic personality and graceful appearance, stands as one of the world’s most beloved goldfish varieties. It’s easy to understand the widespread admiration for these finned beauties.

Comet Goldfish Overview
Comet Goldfish Overview

Dating back to the 1880s, the Comet Goldfish is a result of meticulous selective breeding from the more common Goldfish. This careful genetic crafting has led to a fish that not only captivates our hearts but is also remarkably adaptable. Their ease of breeding has made them widely available – from your local pet stores to being presented as cherished prizes at carnivals. Surprisingly, they’re even sometimes used as feeder bait at angler shops.

Though the Comet Goldfish doesn’t originate from the wild, their care needs closely mirror that of their ancestral counterparts.

Appearance and behavior of Comet Goldfish

The Comet Goldfish is a popular aquarium and pond fish, known for its vibrant colors, swift movement, and relatively simple care requirements. Understanding its appearance and behavior can provide a more fulfilling experience for those who choose to keep this striking fish as a pet.

Colors, Patterns, Fins, and Sex Difference

Comet Goldfish distinguish themselves from other goldfish varieties not only in terms of size but also in their distinct appearance. While they share similar colors and patterns with their goldfish relatives, their body and fin shape set them apart.

One of the most prominent features of Comet Goldfish is their singular V-shaped tailfin, which is responsible for their name and is easily recognizable. Additionally, they have a wedge-shaped dorsal fin that is short and arcs downward along the spine.

Unlike many other goldfish varieties that have a pudgy middle, Comet Goldfish have slender bodies with a thin and narrow physique. They exhibit a range of solid colors, from white to red, although the vibrancy of their coloration can fade with age or due to a poor diet. Some Comets may also display spotted varieties, with spots of different colors adorning their bodies.

Appearance of Comet Goldfish
Appearance of Comet Goldfish

Behavior of Comet Goldfish

Comet Goldfish are bursting with energy and love to explore every nook and cranny of their aquatic playground. This is why a spacious tank is essential, providing them ample room to dart and dash to their heart’s content.

Beyond their playful tendencies, Comets are inherently peaceful and cooperative. Unlike some other species that might get territorial, Comets live harmoniously with other aquatic inhabitants. Their friendly demeanor makes them delightful to both watch and interact with.

Behavior of Comet Goldfish
Behavior of Comet Goldfish

Remarkably intuitive, Comets have a knack for recognizing their human caregivers and can become quite interactive with them. Whether it’s following your finger as it glides along the glass or even playing a game of hide-and-seek behind aquatic plants, they offer more than just visual delight.

It’s important to note that while Comets are temperamentally easy-going, they might not be compatible with all other fish species. This incompatibility often arises from differing habitat needs rather than behavioral issues. Therefore, it’s crucial to consider environmental factors like water temperature, pH levels, and space when adding Comets to a mixed-species aquarium.

How to Take Care of Comet Goldfish

Comet Goldfish are beautiful, lively, and relatively hardy, but like all fish, they have specific care requirements to ensure their health and longevity. Here are some guidelines to properly care for your Comet Goldfish:

Take Care of Comet Goldfish
Take Care of Comet Goldfish

Tank/Aquarium Size

To provide adequate housing for a single Comet Goldfish, it is recommended to have a minimum aquarium size of 50 gallons. For each additional fish, an extra 10 to 12 gallons should be added. Ideally, a Comet Goldfish would thrive in a tank that is 75 gallons or larger. It’s worth noting that if you have a pond, a Comet Goldfish would greatly enjoy the freedom of unlimited swimming space. They are resilient fish that can withstand colder water conditions, making them well-suited for pond-dwelling.

Water Temperature

It’s crucial to place their tank in a location where it won’t be subjected to direct sunlight or excessive heat. An ideal temperature range for the water is between 65° and 72° Fahrenheit.

The water’s pH level range from 7.0 to 8.4. Monitoring and ensuring that these conditions are consistently met will play a pivotal role in keeping your fish healthy and happy.


Selecting the right substrate for your Comet Goldfish’s tank can have both functional and aesthetic impacts. One popular choice among aquarists is sand. It not only offers a natural and appealing look to the tank but also encourages the fish’s instinctual foraging behaviors.

However, a point of contention among hobbyists is the potential for sand to enter the fish’s gills and cause irritation. It’s worth noting that, as of now, there hasn’t been conclusive evidence supporting this concern.


When choosing plants, it’s essential to select those that are compatible with Comet Goldfish. Here are some suitable choices:

  • Java Fern: A hardy plant that’s easy to care for and is known for its unique appearance.
  • Java Moss: Another low-maintenance option, this plant offers a beautiful, carpet-like appearance and is great for covering tank surfaces.
  • Onion Plant: Recognized by its tall and grassy look, this plant is a delightful addition that can reach the surface of larger tanks.
  • Crypts (Cryptocoryne): With various species offering different looks, crypts can add a touch of color and texture to your tank.
  • Amazon Swords: These plants have long, broad leaves and can serve as a stunning centerpiece in your aquarium.
  • Duckweed: This floating plant provides shade and can help control the growth of unwanted algae.
  • Pothos: While not entirely aquatic, pothos can be semi-submerged with its roots in the water, helping to absorb excess nutrients and thus aiding in water purification.
  • Anubias: A slow-growing plant with thick leaves, Anubias is both attractive and durable.


Unlike some other aquatic species, Comet Goldfish don’t require heat lamps. Instead, their lighting needs are focused on replicating the natural rhythm of day and night.

Ensure that their aquarium receives light for a duration of 12 hours or slightly more each day. After this period of illumination, it’s vital to allow the tank to experience a phase of darkness, simulating the natural nighttime environment.


Proper filtration and highly oxygenated water are essential for the health of Comet Goldfish. Without these, they can become vulnerable to bacterial infections and other illnesses. A canister filtration system is suitable for maintaining good water quality for Comets, but it is important to ensure that the water is cycled multiple times per day to keep it fresh and clean.

Are Comet Goldfish Good Tank Mates?

The temperament of Comet Goldfish is rather affable, making them theoretically compatible with a broad spectrum of fish. However, Comets are adapted to colder water temperatures, which might not be suitable for many tropical fish. This divergence in temperature preferences can limit the choices for tank mates.

Another aspect to consider is their size. Due to their smaller stature, it’s vital to be discerning about the other inhabitants of the aquarium. Some larger fish could mistakenly see Comets as potential food.

Conversely, while Comets are generally peaceful, they have a hearty appetite. They won’t hesitate to feast on a tiny tank snail making its slow journey across the tank.

However, despite these considerations, it is possible to find harmonious companions for your Comet Goldfish with careful selection.

Tank Mates
Tank Mates


Breeding Comet Goldfish requires a spacious environment to be successful. They will not breed in a small tank under any circumstances. However, breeding can be achieved in ponds that house large groups of males and females.

During the breeding process, a single female can lay up to 1,000 eggs, significantly increasing the fish population. To initiate breeding, it is necessary to simulate the warm conditions of spring. This can be accomplished by keeping the water cool for approximately one month and then gradually raising the temperature to around 70 degrees Fahrenheit.

Breeding of Comet Goldfish
Breeding of Comet Goldfish

Once the target temperature is reached, the fish will pair off, and the males will actively pursue the females in a lively manner, particularly in a large pond. To encourage successful breeding, it is recommended to use artificial plants or breeding mops. It is crucial to remove the eggs from the breeding environment to enhance survival rates, as Comet Goldfish do not exhibit parental behaviors and tend to consume their own eggs.

In a separate tank, the eggs will typically hatch within a week. Initially, the fry will rely on their egg sacs for nourishment until they become free-swimming. At this stage, suitable food options for the fry include infusoria and baby brine shrimp.

How Much Do Comet Goldfish Cost?

Comet Goldfish are often used as feeder fish due to their size, which is reflected in their pricing. The majority of Comet Goldfish are priced under one dollar per fish, with many ranging from $0.20 to $0.50.

While you can afford to populate your tank with several Comet Goldfish, it is important to exercise caution when pairing them with larger fish. Larger fish may perceive Comets as prey and consume them.

On the other hand, Comets may also mistake other tank inhabitants for food. It is a two-way risk. Therefore, before purchasing multiple small Comets, it is crucial to consider whether your existing fish will accept them, so as to avoid wasting money and jeopardizing the well-being of your aquarium’s inhabitants.


In conclusion, the Comet Goldfish is an ideal fish for an aquatic setup that can accommodate their needs. Due to their potential for growth, they require expansive environments, making outdoor ponds an excellent choice where they can thrive and exhibit their natural behaviors.

Comet Goldfish are best kept in tanks with their own kind or other compatible goldfish varieties, as they may not thrive in diverse community tanks with different species.

It is important to note that Comets prefer cooler water temperatures, so be prepared to regulate and maintain a suitable aquatic environment that meets their specific temperature requirements. Additionally, providing them with proper nutrition is essential for promoting their growth and overall health.

For further aquarium knowledge, explore DryWashAquarium collection of articles to enhance your understanding and create a flourishing ecosystem in your aquatic haven. Remember, informed decisions lead to the best care for your Comet Goldfish.

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Mark Senske
Mark Senske
Mark Senske is a highly regarded expert in freshwater and marine aquascaping, specializing in creating captivating and visually striking aquariums. With his extensive knowledge and experience, he excels in designing and maintaining beautiful aquatic environments that showcase the natural beauty of fish and plants.


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