Beautiful Comet Goldfish Facts

Comet goldfish is the popular aquarium fish due to its beautiful body coloration. It is also called pond comet or comet-tail goldfish. It has deeply forked caudal fin which makes the differences from common goldfish. It is an Atinopterygian  ray finned fish which belongs to the Cyprinidae family under order Cypriniformes. In the early 19th century in the United State, Hugo Mulertt developed it from the common goldfish. It is now one of the most popular and best known fish among the aquarium hobbyists .

Systematic Position

  • Phylum: Chordata
  • Sub-phylum: Vertebrata
  • Class: Actinopterygii
  • Order: Cypriniformes
  • Family: Cyprinidae
  • Genus: Carassius  
  • Species:Carassius auratus auratus

Comet Goldfish Varieties

  • Red and White Comet- Also Known as the Sarasa Comet
  • White Comet
  • Brown Comet
  • Yellow Comet
  • Black  Comet

Shape and Body Coloration

The body is elongated but flat with long and deeply forked caudal fin. The head is short and wide with terminal mouth. The body shows many color patterns including red, white, orange or red and white color combination which makes it a koi color pattern called ‘Kohaku’. At present, several varieties of comet goldfish varieties such as Sarsa, Yellow or Black are available on the basis of color. Among them, Sarasa is the most popular comet variety.   

Size and Lifespan

The highest length of the comet goldfish is 10.16 cm (4.0 inches). It can live up to 14 years or more with  an appropriate and suitable condition.

Quick Comet Goldfish Facts

  • Common Name: Comet-tail Goldfish, Sarasa Comet or Pond Comet
  • Scientific Name:Carassius auratus auratus
  • Adult Size: 4.0 inches (10.16 cm)
  • Temperament: Peaceful and Playful
  • Minimum Tank Size: 15 gallons(57 liters)
  • Tank Region: All
  • Diet:Om​​​​​nivore
  • Water Temperature: 65.0 to 72.0° F (18.3 to 22.2° C)
  • Water pH: 6.0-8.0
  • Hardness: 5 – 19 dGH
  • Water Movement: Moderate
  • Lighting Needs: Moderate – normal lighting
  • Tank Set-up: Freshwater
  • Care Level: Easy-medium
  • Lifespan: 4-14 years

Feeding Behavior

Comet goldfish eats both plants and meaty food such as  algae, plant matter, insects, its larvae and small crustaceans such as Cyclops, Daphnia,  Moina, Naupleus larva etc. In aquarium condition, they take different types of live foods such as Chironomus larvae, Artemia or brine shrimp, Tubifex worms. Frozen and flake foods are also favorite for comet goldfish. You may also offer fresh or parboiled vegetables such as cucumber, peas, zucchini, broccoli, carrots and romaine lettuce. To keep a good balance for your fish, you should offer them a high-quality flake food daily.  Feeding should be done 2-3 times each day.

Housing and Care Facts

Comet goldfish is hardy and easy to care for. They need 15 gallons tank  or larger with plenty of swimming space. To make a comfortable and natural environment, you should use gravel or driftwood substrate. In this case, gravels or driftwood should be smooth with no protruding points or edges. You may also use live or artificial aquarium plants  to decor your aquarium. The ammonia should always be 0 mg/l and the nitrate should be below 20mg/l.

To keep your fish healthy tank water should be replaced on a regular basis. In this case every other week at least 25 – 50% of the tank water should be replaced, especially if you keep more fish in the tank. For maintaining proper water quality in the aquarium, the tank should have biological filtration. This type of filtration can create clean water by eliminating the excess foods, detritus and wastes.  This filter also help to maintain the good health of fish and other aquarium inhabitants. Snails can also be added as they reduce the algae in the tank, helping to keep it clean.


It is a peaceful fish and you can keep  them with other Pond Comets, Shubunkins, Koi, and Butterfly Koi. It should not be kept with slower twin-tails like Ornanda, Black Moors, Veiltail, Telescope Eye or Ryukin goldfish due to competition for food.

Breeding Behavior

Comet Goldfish is an egg layer that spawns readily in captive condition with proper care. The breeding tank should have solid surfaces. In this case, oxygen producing plants, such as Anacharis does well.  Artificial plants or fibrous spawning mops can also be used. In wild condition, the comet goldfish breeds during spring season. They can breed in groups as small as five or more individuals due to their very social and peaceful behavior.

Water parameters influence breeding behavior of comet goldfish. In this case, a breeding tank should have good water parameters with a pH of 6.0-8.0, hardness of 4-19 dGH while temperature should be between of 65.0 and 72.0° F (18.3 and 22.2° C).

Before spawning,  the brood fish should be conditioned using high protein food such as live brine shrimp or Artemia and worms. Partial water changes of up to about 20% per day should be done to maintain the good water quality in the aquarium. The sexually mature female can produce up to 10,00 0 eggs which adhere by sticky threads to the plants or spawn mop and spawning can last two or three hours. After spawning, the parent fish should be removed from breeding tank to inhibit them from eating the eggs or fry. The fertilized eggs hatch within 4 to 7 days. After 24-48 hours, the fry become free-swimming. In this stage, fry need proper food and they can be fed with infusoria, newly hatched Artemia (baby brine shrimp) or commercially available fry foods.

Male and Female Sex Differences

At the young or juvenile stage,  the male and female fish differentiation is very hard. Generally, the male is smaller and more slender than the female. During the breeding season,  breeding tubercles are seen in gill covers  and head in male fish while a sexually mature female has a fatter appearance when she bears eggs in her belly.

Also Read:  Goldfish Illness: Treatment And Prevention Measures

Concluding Remarks

The comet goldfish is  very hardy and  excellent for the beginner aquarists. It is now the world’s most common goldfish variety.  It is characterized with a long slender body and long single deeply forked caudal fin with varieties color pattern which make it more attractive among the ornamental fish keepers. It is inexpensive and readily available in fish stores and online vendor.

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