Beautiful Comet Goldfish Facts

Comet Goldfish is one of the most beautiful ornamental aquarium fish. It is also referred to as Comet-tail Goldfish or Pond Comet. It can be distinguished from the common goldfish by its long, single and deeply forked caudal fin. It belongs to the family Cyprinidae under order Cypriniformes of class Actinopterygii. In the early 19th century, it was developed in the United States from the common goldfish by Hugo Mulertt. It is now one of the best known and most popular fish in the aquarium hobby.

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 Comet Goldfish has an elongated and flat body with short and wide head. It has many colors and color patterns including orange, red, white or red and white color combination that looks a koi color pattern called ‘Kohaku.’ Occasionally it is available with nacreous or pearly scales giving them a variegated color. It has long and strongly forked caudal fin that stands fully upright. On the basis of color variation, there are several varieties of comet goldfish such as Red, Sarasa, Yellow or Black. Among them, the most popular comet variety is known as the Sarasa.

Size and Lifespan

It can grow 4.0 inches (10.16 cm) in length and can live up to 14 years or more under a 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 is omnivorous and in wild it feeds on plant matter, algae, insects and small crustaceans. In captive condition, it generally eats all kinds of fresh or live foods such as brine shrimp, blood worms, Daphnia or Tubifex worms, frozen and flake foods. It also accepts plenty of parboiled fresh vegetables such as peas, zucchini, cucumber, broccoli, romaine lettuce, and carrots. You should offer them a high-quality flake food every day to keep a good balance. Feed should be offered 2-3 times daily.

Housing and Care Facts

Comet goldfish is hardy and easy to care for. It requires at least 15 gallons tank with lots of swimming space. The tank should have gravel or driftwood substrate which provide a natural and comfortable environment. The gravels or driftwood should be smooth with no protruding points or edges. Aquarium plants should be used to décor your aquarium. In this case, live or artificial plants make a good substitute. 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. Good filtration especially biological filtration is required for maintaining the water quality of the aquarium. Because this filtration system removes detritus, excess foods and wastes which help to keep the tank clean and maintain the general health of the fish in the aquarium. Snails can also be added as they reduce the algae in the tank, helping to keep it clean.


It can be kept 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 the spawn during spring season. It is very social and peaceful fish which likely to breed in groups as small as five or more individuals.

Water parameters influence  breeding behavior. In this case, a breeding tank should have good water 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 parent should be conditioned with high protein food such as live brine shrimp 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 eliminated from the 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 stage, it is difficult to make differences between the male and female fish. Generally, the male is smaller and more slender than the female. During the spawning season, the male has breeding tubercles in gill covers and head which are seen as white prickles while a sexually mature female has a fatter appearance when she bears eggs in her belly.

Concluding Remarks

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

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