Common Goldfish


Family: Cyprinidae Goldfish, Common Goldfish, Carassius auratusCarassius auratus auratusPhoto © Animal-World: Courtesy David Brough
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My daughter just won 5 common goldfish at a local carnival. Are they okay overnight (fish stores are closed), what size tank should we get, and are they... (more)  Michelle

Goldfish are fun to watch... just look at all the different colors of these beautiful fish!

The Common Goldfish are colorful, inexpensive, and readily available. For about 90 percent of all aquarists, their first fish were Common Goldfish won at the local faire or obtained from the pet store in town. They can be quite personable and are delightful to watch.

One of the hardiest of the gold fish varieties, the Common Goldfish are recommended for beginners. They are an easy fish to keep as they are not picky and will readily eat what is offered. They are active and can swim fairly fast. They are also very social and thrive well in a community.

Picture of a Common GoldfishCommon Goldfish Picture of a Comet Goldfish Comet Goldfish

The Common Goldfish is very similar to, and sometimes confused with, the Comet Goldfish. The Comet Goldfish is a further development of the Common Goldfish. Both these fish have an almost identical body shape but the fins on the Comet are much longer, especially the caudal (tail) fin, and it is more deeply forked. Also, in the standard orange color the Comet is generally a more reddish orange while the Common Goldfish is more orangish. The adult size of the Comet Goldfish is smaller too. On both these fish the caudal (tail) fin is held fully erect.

Another goldfish that is almost identical to the Common Goldfish is the 'London' type of Shubunkin Goldfish. Both these fish have virtually the same body and fin shapes, but the London type Shubunkin Goldfish has a totally different body color. While a good specimen of the Common Goldfish will have a bright orange metallic color, this London type Shubunkin goldfish can be speckled or have a variegated color pattern.

Along with the other elongated goldfish, such as the Comet Goldfish and the Shubunkin Goldfish, Common Goldfish make good pond fish. They are hardy and can tolerate cold water temperatures. They are active and fast and can get along well with Koi, but they will readily spawn so can quickly overpopulate your pond.

For more goldfish information, see:
Goldfish Care: Fancy Goldfish and Goldfish Diseases

Geographic Distribution
Carassius auratus auratus
Data provided by
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Cypriniformes
  • Family: Cyprinidae
  • Genus: Carassius
  • Species: auratus auratus
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Common Goldfish - Quick Aquarium Care
  • Size of fish - inches: 14.0 inches (35.56 cm)
  • Minimum Tank Size: 25 gal (95 L)
  • Temperament: Peaceful
  • Aquarium Hardiness: Very Hardy
  • Temperature: 65.0 to 72.0° F (18.3 to 22.2° C)
  • Aquarist Experience Level: Beginner
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Habitat: Distribution / Background

The goldfish of today are descendants of a wild carp fish, known as the Prussian Carp, Silver Prussian carp, or Gibel Carp Carassius gibelio (syn: Carassius auratus gibelio) which was described by Bloch in 1782. For many years it was believed that goldfish had originated from the Crucian Carp or Golden Carp Carassius auratus auratus described by Linnaeus in 1758, but more recent research is pointing toward the former. These wild carp originated in Asia; Central Asia (siberia). They inhabit the slow moving and stagnant waters of rivers, lakes, ponds, and ditches feeding on plants, detritus, small crustaceans, and insects.

In the early 1500's these fish were exported first to Japan and then to Europe and were developed into the wonderful colors and forms of gold fish we see today. The Common Goldfish is one of the more than 125 captive bred varieties that have been developed.

  • Scientific Name: Carassius auratus auratus
  • Social Grouping: Groups
  • IUCN Red List: NE - Not Evaluated or not listed


The Common Goldfish is an elongated, flat-bodied variety of goldfish. The head is wide but short and it has a smoothly tapering body shape from its back and belly to the base of its caudal fin (tail fin). The caudal fin is forked. Its fins generally stand fully erect and the edge of the dorsal fin is slightly concave.

  • Goldfish colors
    The most distinguished specimen is a bright orange metallic color.
  • Size - Weight
    The environment the Common Goldfish is kept in is a determining factor on whether your pet grows to its full potential size or is somewhat smaller. In an average 10 gallon tank, if well cared for and not crowded, they can grow up to about 4 inches (10 cm), while in a larger uncrowded tank they can grow larger generally reaching about 7 or 8 inches (17.78 - 20.32 cm). If kept in a spacious pond they can reach over 12 inches (30+ cm), with some hobbyist reporting their Common Goldfish reaching up to a whopping 18" (45+ cm)!
  • Goldfish lifespan
    The average goldfish lifespan is 10 – 15 years, though living 20 years or more is not uncommon in well maintained goldfish aquariums and ponds.
  • Size of fish - inches: 14.0 inches (35.56 cm) - In a pond this fish will grow much larger, if subjected to poor conditions and a small tank this fish will die young, stunted, and probably deformed.
  • Lifespan: 20 years

Fish Keeping Difficulty

Common Goldfish are some of the hardier species of goldfish. They are very undemanding of water quality and temperature. They can do well in goldfish aquariums, a pond, or even a goldfish bowl when small, as long as the environment is safe and their tank mates are not competitive.

Many people will keep goldfish in small one or two gallon goldfish bowls with no heater or filtration. But for the best success in keeping goldfish, provide them the same filtration, especially biological filtration, that other aquarium residents enjoy.

  • Aquarium Hardiness: Very Hardy
  • Aquarist Experience Level: Beginner

Foods and Feeding

Since they are omnivorous, the Common Goldfish will generally eat all kinds of fresh, frozen, and flake foods. To keep a good balance give them a high quality flake food everyday. To care for your goldfish, feed brine shrimp (either live or frozen), blood worms, Daphnia, or tubifex worms as a treat. It is usually better to feed freeze-dried foods as opposed to live foods to avoid parasites and bacterial infections that could be present in live foods.

  • Diet Type: Omnivore
  • Flake Food: Yes
  • Tablet Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Vegetable Food: Some of Diet
  • Meaty Food: Some of Diet
  • Feeding Frequency: Several feedings per day

Aquarium Care

Regular weekly water changes of 1/4 to 1/3 is strongly recommended to keep these fish healthy. Snails can be added as they reduce the algae in the tank, helping to keep it clean.

  • Water Changes: Weekly

Aquarium Setup

Setting up an aquarium in a manner that will keep your fish happy and healthy is the first step to successfully fish keeping. Here are aquarium parameters to consider in choosing goldfish aquariums, filtration, lighting, and decor as well as temperature and water movement.

  • Minimum Tank Size / Length:
    The shape and size of the goldfish aquarium is important and depends upon the number of fish you are going to keep. Goldfish need a lot of oxygen and produce a lot of waste. Keep the tank size and shape in mind when you are buying your fish.
    • Tank Shape
      A large surface area of water will help minimize goldfish suffering from an oxygen shortage. Surface area is determined by the shape of the tank. For the same volume of water, an elongated tank offers more surface area (and oxygen) than a tall tank. In a goldfish bowl, filling the bowl to the middle offers more surface area than filling the bowl to the top. Always provide the maximum amount of surface area.
    • Tank size
      It's best to start with a 20 - 30 gallon tank for your first goldfish and then increase the size of the tank by 10 gallons for each additional goldfish. Providing a large amount of water per fish will help dilute the amount of waste and reduce the number of water changes needed
    • Formula: # of fish per gallon of water
      A general rule of thumb, but only for young fish, is 1 inch of fish (2.54 cm) per 1 gallon of water. This rule applies only to young fish and is not adequate as they grow. Larger gold fish consume much more oxygen than young fish so maintaining this formula for growing fish will stunt them, and can contribute to disease and even death.
    • Fish: size and growth
      To allow for growth, either buy fewer fish than the maximum number of fish (based on the formula above) or be prepared to get a larger tank. Larger gold fish consume much more oxygen than young fish so maintaining this formula for growing fish will stunt them, and can contribute to disease and even death
  • Aquarium Lighting
    Most aquariums come with a cover that includes lighting. A cover for the tank is desirable as it reduces evaporation and though they are not prone to jumping, on occasion some gold fish will jump out. Lighting is not essential for goldfish, but does make the aquarium a nice show piece and lighting will help if you have live plants.
  • Filtration
    Goldfish produce a lot of waste. Good filtration, especially biological filtration, is very helpful in maintaining the water quality of the aquarium. Filtration systems remove much of the detritus, excess foods and waste. This helps keep the tank clean and maintain the general health of the goldfish.
  • Substrate
    Provide a gravel substrate to help create a natural and comfortable environment for your fish. A medium sized gravel works best..
  • Aquarium Decor
    You can add some decor, but make sure that all ornamentation is smooth with no protruding points or sharp edges. Smooth rocks or driftwood, should be used sparingly if at all.
    Aquarium plants would be the best choice of aquarium decor for goldfish, but unfortunately these fish are diggers. Consequently live plants may be uprooted. Artificial plants make a good substitute and silk plants are safer than plastic ones.
  • Temperature: Goldfish are a cold water fish and will do best at temperatures between 65 - 72° F (18°- 22° C). The Common Goldfish is one of the most hardy varieties of goldfish and can tolerate temperatures a few degrees above freezing, as long as the cooling drops only a few degrees a day. A quick temperature drop can kill them, so if you live in a very cold climate a heater is advisable.
  • Water Hardness: 5 - 19° dGH
  • ph: 6.0 to 8.0
  • Water Movement: Moderate.
  • Water Region: These fish will swim in all areas of the aquarium.

Picture of Common Goldfish, Carassius auratus

  • Minimum Tank Size: 25 gal (95 L) - This fish can grow to over a foot in length, keeping it in a small tank will horribly stunt its growth and cause irreversible damage. 25 gallons is really the absolute minimum suggested for this variety of Goldfish.
  • Substrate Type: Any
  • Lighting Needs: Moderate - normal lighting
  • Temperature: 65.0 to 72.0° F (18.3 to 22.2° C)
  • Range ph: 6.0-8.0
  • Hardness Range: 5 - 19 dGH
  • Brackish: Sometimes - Goldfish are freshwater fish, but they have some tolerance for slightly brackish water. Yet any salinity for C. auratus must be kept below 10%, a specific gravity of less than 1.002.
  • Water Movement: Moderate
  • Water Region: All

Social Behaviors

Goldfish are very social animals and thrive in a community. Not only are they a great community fish but they are great scavengers as well. It is really not necessary to add other scavengers or other bottom feeders to the aquarium when you have goldfish.

Most fancy goldfish will thrive in both freshwater and tropical aquariums as long as there are no aggressive or territorial fish in the tank. Some good tank mates for fancy goldfish are the Chinese Blue Bitterling and the Northern Redbelly Dace.

Common Goldfish can be kept with other varieties of elongated goldfish, such as the Comet Goldfish and the Shubunkin, and they also do fine with Koi.

  • Venomous: No
  • Temperament: Peaceful - This fish is active and friendly.
  • Compatible with:
    • Same species - conspecifics: Yes
    • Peaceful fish (): Safe
    • Semi-Aggressive (): Threat
    • Shrimps, Crabs, Snails: Safe - not aggressive
    • Plants: Threat - Goldfish produce more waste than most other freshwater fish and benefit greatly from more frequent water changes.

Sex: Sexual differences

Although is it impossible to sex Goldfish when they are young and not in breeding season, the male is usually smaller and more slender that the female. In the breeding season the male has white prickles, called breeding tubercles, on its gill covers and head. Seen from above the female will have a fatter appearance as she is carrying eggs.

Breeding / Reproduction

Common Goldfish are egg layers that spawn readily in the right conditions. See Breeding Freshwater Fish - Goldfish for more information on breeding Goldfish.

  • Ease of Breeding: Easy

Fish Diseases

Goldfish are subject to the same diseases as tropical fish. A couple of the more common problems are Ich, Swim Bladder Disease, and external parasites including flukes, lice and anchor worms. For more in-depth information about goldfish diseases and illnesses, see: Goldfish Care; Fancy Goldfish and Goldfish Diseases.


The Common Goldfish is readily available in fish stores and on-line, and is inexpensive


Author: David Brough CFS.
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Lastest Animal Stories on Common Goldfish

Michelle - 2010-05-08
My daughter just won 5 common goldfish at a local carnival. Are they okay overnight (fish stores are closed), what size tank should we get, and are they okay until morning without a tank? The only options we have are a 1 gallon betta kit and a 10 gallon aquarium (we don't have the water or conditioner for the 10 gallon)?

  • Anonymous - 2014-06-03
    Ok, first of all you need more than a ten gallon tank. Number two, look on this website if you need help. It works wonders for me.
cassiopeia - 2009-12-28
Goldfish must be the most neglected pet ever. I work in a petshop and am constantly bombarded...! One woman came in asking for a goldfish bowl, I told her why we don't stock them and how bad they are for fish. She paused for a minute then said, the garden centre sells them and would she need a small one cos she only wanted 2 small goldfish! I had to bite my tongue, then tryed explaining that goldfish can reach up to 14" and live to around 20 years with the proper care and attention! None of which sunk in, and I know that she probably went to the garden centre where they'll sell anything to make money. I admit I've had my share of beginners mistakes, but my goldfish I've had since I was 5, only passed away 2 weeks ago at a grand age of 15! Also my 1st shubunkin was 10 when he sadly passed on! and I feel they could have been kept better. They were in a 3ft jewel aquarium with only live plants and 1 feed a day, but they could have done with a 4 or 5 foot tank. I took on a new comet goldfish from a man who was moving home and couldn't take poor "sharky" with him. He is almost 1ft in length and is 14 years old, he has a deformed spine and his pectorial fins are tiny, curved up and quite useless! This may have been from a bacterial infection or possibly because his tank was ridiculously undersized! Anyway thats quite enough ranting for one day, the bottom line is don't buy bowls or tiny plastic boxes for goldfish. They need a really good filtered tank, 2ft to start with as long as you're prepared to save up for a larger tank for when your fish grows. Provide live plants for decor an food (they also improve water quality) and always use tapsafe as water companies sometimes add new chemicals to the water.
Hope this rant is listened too and acted upon! (big fish need a big tank)

  • Lucky - 2010-10-03
    Will goldfish get along with some other fish, like, um, maybe catfish or some other fish that's larger than the goldfish is? Or will it get eaten? =(
  • jenna morris - 2011-01-31
    At my old apartment complex my landlord came to me with over 30 baby commons in a 10 gallon tank that had been abandoned. First thing I did was go buy a 50 gallon tank and start an adoption program. I hit the web looking for how to care for them all but one was adopted. We named him piggy. He is now a spry 6 years old and thriving. I'm saving for a bigger tank! I agree with you. People don't see fish as the wonderful part of the animal kingdom they are. I keep up with piggy's brothers and sisters as best I can. To me they're like abused rescued children.
Silvia - 2003-12-28
although beautiful and hardy...My suggestion for stocking levels is 1 fish per gallon of water. Also, these fish have the most amusing habit of rummaging around in the substrate, by working gravel in and out of their mouths searching for anything edible.These are hardy fish which can tolerate a lot, but please dont use that as an excuse to mistreat them.

  • Gavin - 2014-04-09
    1 gallon per fish is not sufficient it must be at least 15 gallons per fish.
  • Anonymous - 2014-06-03
    One gallon of water per inch of fish is better for healthy goldfish.
  • Rachel - 2014-06-04
    We tend to use the rule one gallon for every inch of fish. For a five inch fish you need five gallons of water, a three inch long fish needs three gallons of water, and three one inch fish will also need three gallons of water. For all of these fish together in one tank the bare minimum would be 11 gallons.
Andres - 2009-10-31
I don't understand how most of the people that have postd here are proud to have overstocked fish tanks / aquariums. A goldfish needs a minimun of 20 gallons for one goldfish and then add an extra 10 gallons for an extra goldfish. Some people are proud to have as little as 5 litres, 15 litres or 10 gallons, which none is goon enough even for 1 goldfish. If people bothered to read even a little about how to care for their pets (goldfish) they would not be so proud to learn that they're not caring for them properly and how misrable their poor fish must be.

I can not stress enough how important it is to get the right size tank in orderto keep healthy goldfish and just because some goldfish manage to live for 2 or3 years in very poor conditions, it doesn't mean that those 2 or 3 years were not agony for the poor fish. I can't think nothing crueler than sujecting your own pet to that kind of torture. It would be more humane to acctually kill it than inflict all that suffering for that period of time. If you are going to have pets then the least they deserve is to be cared for properly. Please Please Pleae people read up on how to take care of goldfish properly

mason - 2008-06-19
I enjoyed reading your interesting page about goldfish care (I found it while googling reproduction) and I decided to add my two bob's worth: yes, they are easy to care for as long as you keep them well fed and cleaning out their tank every few weeks. A good filter also really helps keep the water cleaner and aerated as well. We've got two fish - Wiggles, an ordinary goldfish and Dingleberry, a hyperactive Shubunkins. They both get along well together, really cosying up to each other at times... Another time we saw Dingleberry chasing Wiggles all around the tank - it was hilarious watching Wiggles frantically trying to escape his "amorous" attentions...

Goldfish are also more intelligent than you might think; Wiggles and Dingleberry always know when it's feeding time and they get terribly excited when they see me approaching their tank around feeding time!

We've just upgraded to a larger tank (15 litres) which replaced their old (and tiny) 5 litre job, and they just love it! I added a pictorial backing as well as more rocks and artificial weed for a more natural look and I also think that this more stimulating environment is definitely helping the fish as well as providing them with more room to swim and exercise.

Marcus Barber - 2004-07-16
I first bought 15 feeder goldfish at 5 for a dollar 3 years ago. The nice lady at the pet store gave me one extra. They were only about an inch long. In the past 3 years 3 have died but the rest are between 5 and 6 inches long. They seem to be growing too fast but that is probably only because I have kept them in an outdoor tank. I guess you could call it a tank it is actually a huge tractor tire that is approximately 450 gallons and is directly hooked to a well and has water available anytime. There is a faucet thing underwater that is tied to a plastic float. All I have to do is push the float down and water comes out. The tank is about 4 foot across and 3 foot deep. I keep them there all year round even in the winter. It freezes about 2 inches solid every year about every day in the winter. I am only 14 years old so I`m out of school during the winter because of snow so I have this sledge hammer to bust the ice gently so not to scare the fish. The tank doesn`t have any sort of filtration just when I dip out about 10% of the water every day.


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