Gold Comet Fish – Lifespan, Size, Diet, Care Guide

The gold comet fish is ideal for home aquariums and all for good reasons. From its hardy nature to the blossoming colors that bless every room they are kept in; this fish makes a great value for your money.

The fish also comes in a variety of colors besides the common yellow- and orange-colored ones. Scientists have made sure of this by introducing the selective breeding technology that has seen to the production of other interesting colors.

It is also the reason why this fish goes by several names such as black comet goldfish and single-tail goldfish.

When taken good care of, the fish can fill your room with color for up to 14 years and grow to a length of up to 30 centimeters.

With current diseases that are slowly becoming pandemics such as Alzheimer’s disease, medical practitioners have proven that keeping a bright-colored fish such as the these fish could lessen anxiety among patients, more reason to have one in your aquarium.

Gold Comet Fish Origin

This fish has its ancestral roots deep in the rivers and streams located near North America. It all goes back to the 19th century when the founding pioneer Hugo Mulertt who was seemingly just doing his job of breeding fish at the U.S Government Fish Commission ponds stumbled upon this beautiful breeding outcome.

It was named the ‘gold comet fish’ because it had a long thin golden tail that resembled a comet’s shape.

Today, the name is highly appreciated all over the world. Walk into any residential and commercial buildings and you might just have a glance of this colorful fish, well, that’s if you don’t get one for your home.


Comet Goldfish
Gold Comet Fish

The gold comet fish tends to have slight differences from the common goldfish. A particularly peculiar difference is the flowing fins it has as compared to the inflexible ones of the common fish.

Note, however, that it is not natural for your comet goldfish to turn black. If you spot this anomaly, get in touch with an expert for advice.

All the brightness of this fish is courtesy of the flat shining scales laid perfectly on their bodies. In addition to the typical golden variants of this species, additional shades such as white and red (commonly known as Sarasa Comet Goldfish), black comet goldfish (which are basically koi hybrids), and brown are also available for the picking.

Recent variants such as the Shubunkin Goldfish have proven to brighten any room with their cloud-like body color.

The fish takes only 4 years max. to attain its full size of 12 inches with a growth rate of 50% of its body size every week when properly taken care of.

Care Guide

Comet goldfish just like any other species, will only thrive and live longer when properly taken care of. In this section of the article, we will look at its dietary requirements, tank requirements as well as ideal water conditions to ensure your pet is happy and brightens your day for a long time.

Dietary Requirements

To understand what is the favorable diet for this fish, we build our foundation based on what it feeds on in the wild. Plants, small animals, and insects form their major diet components in their original habitat. This makes them omnivores.

In your tank, feed them something to resemble this to ensure that their coloration remains fresh and healthy. Meaty foods such as ants, small insects, blood worms, and mosquito larvae could do just the trick.

Fiber and nutrients could be found in rich vegetables such as cucumber crumbs, algae, plant roots, broccoli, carrots, and mashed peas. This fish also appreciates artificial feeds such as flakes and pellets.

Comet goldfish have n huge appetite, which could be both a good thing because the nutrients will make them grow faster and a bad thing because overfeeding may result in bloating and other digestive issues. A good feeding schedule would be 2 to 3 times a day.

Only put enough food to be consumed within two minutes. Try to remove the leftover food from the tank to maintain balanced water conditions.

Pro Tip: Science has it that if the fish feed underwater conditions that are below 50 degrees Fahrenheit, they may be subjected to digestive complications. You don’t want that, do you?

Tank Requirements

Comet Goldfish Tank
Comet Goldfish Tank

Comet goldfish are not the choosiest of pet fish, but given their color is of massive important to the keeper, there are things you need for your tank to ensure your goldfish thrive.

Recommended Tank Size

The ideal tank size would be a 75 gallon one, however, a 40 gallon tank could do just fine. It is actually really wrong to live by the myth that goldfish only grow to the size of the tank they have been kept in.

Avoid this myth like plague (even if a pet store tells you that). Keeping your fish in a small space could be really detrimental to their health as well as well being.

How many in a tank ?

As a general rule of thumb, 50 gallons should host only one comet goldfish. Therefore, in case you have two, double the size of your tank.

Decorations and Plants

Decorating your tank with stone chips, caves, small gravels, and a good amount of substrate will not only enrich the water with quality minerals but will also offer a sanctuary for your pet from other predator fish in your tank.

Plans offer an excellent natural way of filtering tanks by oxygenating the water as well as a good hiding and resting place for the fish. We recommend freshwater plants such as the java fern and hornwort.


The tank needs to be adequately lit for a healthy lifestyle. A moderate light fixed to the top of the tank would do great. You don’t want to fix a really bright one that will end up heating up the water instead.

To avoid excessive heating of the water, turn the light just about 10 hours a day and turn it off at night to allow the water to regain its normal temperature.


Bacteria tend to pile up in aquariums over time. This is why you need a quality filter that will break it down and hold chemicals and waste from your fish at bay. This will ensure that the water conditions remain ideal for your fish to thrive in and reduce the chances of sickness.

Water Conditioner

Your filter will break down what you can see with your naked eye; but what about the unseen chemicals and germs that may have detrimental effects on your precious fish? This is why you need a quality water condition to ensure stability in the water conditions.

Ideal Water Conditions

After getting your tank for your pet, you are now left with setting it perfectly for your treasure. There are some basics you need to adhere to lest your fish is destroyed by poor water conditions. Let me run you through the most important;


As mentioned earlier, water temperature is a key factor especially for their survival  as well and digestion. In the wild, the fish thrives in cold water lakes and cannot live in warm water. A temperature range of 50 to75°F (10 to 23°C) is ideal.

Water pH levels

Anything between 6.5 to 7.5 on the pH scale is great. This is vital as highly acidic water could degrade their skin.

Water Hardness

Target to achieve water hardness of about 5-19 dGH.

Cleaning the Tank

There are three main items to be cleaned in your tank when need be; the gravel, the walls and decorations, and the water itself. One thing is clear, there is no need of removing the fish out of the tank nor the water while cleaning.

For the gravels at the bottom of the tank, a gravel vacuum could do the work perfectly.

For the sides of the tank and the decor, use liquid soap and a soft brush to clean. After you are done, use a clean piece of cloth to wipe dry the objects.

The water replacement procedure should be a gradual one. A famous way that works great is changing the water by 10% weekly. However, changing the water monthly by about 28% isn’t bad at all.

Be keen to check the water parameters such as hardness and temperature of the water during this replacement procedure. Doing all this will ensure a healthy and vibrant life for your fish.

Ideal Temperature

Pet enthusiasts always have the comet goldfish at heart since it is pretty easy to take care of and quickly adjusts to the environments of the tank.

In addition, since the fish is small, a small tank of about 50 gallons serves it well. This tank size doesn’t occupy much space in buildings increasing the pros for having this fish.

It is glorious to watch this fish swim gracefully exposing its bright colors that are heartwarming. Because of this fact, you need to have a spacious tank that won’t be a hindrance to its reckless swimming and love for the exploration of the tank it is kept in. It also means that you will have to minimize the number of fish you keep in the tank alongside this fish.

Once you have purchased your fish and started feeding it, over a period, this intellectual fish will be inclined to you. It will expect you to feed it and maybe aggressive to any other person that the fish isn’t familiar with trying to feeding it.

Suitable Tank mates

Even though most of us love keeping several different species of fish in the same tank, unfortunately, that might be limited when talking of the comet goldfish. Goldfish eat lots and lots of food and may subject its tank mates to malnutrition and even starvation to death in the worst-case scenario.

This however should not demoralize you from having tank mates as there are several similar sized fish that we recommend for you including guppies, dojo loaches, rosy barbs, zebra danios, bristlenose pleco, and weather loaches. Even with these, be keen not to overcrowd the tank.

In case you are wondering if you can keep more than one of the adorable comet goldfish in one tank, the answer is yes.

Just ensure you have a large tank enough to host all of them and offer adequate space for swimming. For instance, if you are keeping two, a 100-gallon tank is in order.

In the goldfish community, variants such as the common goldfish, shubunkin goldfish, and wakin goldfish make suitable tank mates while others like the celestial eye goldfish, bubble-eye goldfish don’t.

Aggressive and bigger species as well as those that are extra small should be avoided at all costs. Such include shrimps, snails, celestial eye goldfish, bubble-eye goldfish, and flowerhorn.

Comet goldfish feast on crustaceans and invertebrates for their animal protein. Therefore, these won’t make suitable tank mates.

Comet Goldfish Breeding

In a natural setting, the spring makes the ideal phase for the breeding of the comet goldfish as temperatures of rivers and ponds are normal. In an aquarium setting, you will be required to raise the temperature a little up to 58°F (14 °C) during the first month and late gradually increase it to 70°F (21°C).

It is during this time that lighting your tank is important, as it will trigger the spawning behavior of this fish. For a start, light the tank for about 12 hours during the day.

To begin, you need to correctly differentiate the male from the female. The male has white prickles commonly known as breeding tubercles well placed on its gill covers and the head. The female will have a bulging stomach because of the eggs its carries and is seemingly fatter.

Breeding this fish in a home setting tank isn’t a walk in the park. This is since the fish needs a spacious environment with suitable water parameters to breed. When the female is about to lay eggs, it is advisable to acquire another tank from which it can feel comfortable and lay eggs.

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