Goldfish Facts

The goldfish (Carassius auratus) is one of the most popular aquarium fish which belongs to the Cyprinid family (Carp family) of order Cypriniformes. Today, all descendants of the goldfish come from Prussian carp which is native to Eastern and Southeast Asia. Goldfish is related to carp but not the same as carp. Goldfish can be differentiated from the koi carp and common carp by the lack of barbells or whiskers which are located in the corners of their mouth. About a thousand years ago, goldfish first selectively bred in Ancient China and brought indoors achieving gold, red, spotted and other colored fish. At present, several distinct breeds have been developed. In the pet fish market, there are lots of goldfish breed available which greatly vary in body shape, size, fin patterns and body decoration. They include comets, fantails, bubble eyes, orandas, celestial eyes, ryukins, moors, telescope eyes, butterfly shubunkins, lionheads, pearlscales, wakins, ranchus and many more.


Goldfish are available in all pet fish stores around the country as the most popular fish which come from commercial breeders. There are many goldfish breeders who breed goldfish commercially, usually located in Thailand, Japan, China or Indonesia. Generally, commercial goldfish have yellow, gold or other colors while the color of the wild or untamed goldfish is nearly olive green or dark grey in color. Commercially produced goldfish are suitable for indoor living only. Among them, there are some goldfish species that survive in outdoor water garden and ponds and can grow there much larger.

In nature, goldfish prefer to live in all the freshwater bodies from temperate to tropical environments such as rivers, streams, lakes, ponds where slow-flowing, thick muddy and calm waters are available. They also like stagnant backwaters, where they feed on plenty of aquatic plants. In many parts of the world, goldfish have been introduced to control mosquito populations.

In captive condition, on average, the goldfish can live up to 10 years or more if we take proper care. If you keep them in a bowl, they show the shortest life expectancy. But if you keep them in a water garden or pond, they can live up to 20 years, sometimes up to 40 years. But many goldfish do not attain their lifespan due to incompetent housing conditions. The common goldfish is one of the largest species of the goldfish which can reach over 18 inches in length and up to ten pounds in weight.

Systematic Position

Phylum: Chordata
Sub-phylum: Vertebrata
Class: Actinopterygii
Order: Cypriniformes
Family: Cyprinidae
Sub-family: Cyprininae
Genus: Carassius
Species: Carassius auratus (Linnaeus, 1758)

Food and Feeding Behavior

Goldfish are omnivores and in the wild condition, their food comprises crustacean’s zooplankton such as Daphnia, Cyclops, Moina etc, Insects, its larvae, frogs, newts, bloodworms, fish eggs and various aquatic plants parts. In captive condition, they take pellet fish food, Chironomus larvae, Tubifex, green leafy vegetables and shelled peas. For the young goldfish, you should offer Artemia or brine shrimp. Generally, the diet should contain less protein and more carbohydrate than conventional fish food.

As a good staple food, you may give them a mixture of goldfish flake and granules. It should be supplemented with live brine shrimp (=Artemia) and a mixture of frozen brine shrimp, Daphnia, small invertebrates, duckweed and veggie mix. If you use any freeze-dried food, it should be soaked first to avoid digestive troubles of fish. Feeding of your fish should be done 2-3 times daily. Overfeeding should be avoided to prevent indigestion or contamination the tank.

Water Requirements

Goldfish aquarium should have good water quality. To keep water quality suitable for fish, you should test your water for pH, CO2, DO, Hardness, ammonia, nitrite and nitrate levels using water testing kit.

Actually, goldfish is a cold water fish but you can keep them in heated aquariums. The suitable temperature for goldfish ranges from 60° to 74° F (18-23 °C) while pH should be between 6.0 and 8.0 to keep your fish healthy. For making optimum tank environment, 20-25% water changes should be done every 2-4 weeks. In this case, you can use Aqueon Aquarium Water Changer or Siphon Vacuum Gravel Cleaner.

Suitable Water Parameters For Goldfish

• Ammonia: <0.1 mg/l
• Nitrite: <0.2 mg/l
• Nitrate: <50 mg/l
• Water pH: 6.0-8.0 (tolerance range: 5.0-9.0)
• General Hardness (GH): 5-19 dGH
• Water Temperature: 60° to 74° F (18-23 0C)

Housing and Care Facts

Goldfish are the most popular of all ornamental fish due to their attractive body shape and bright colors. They are very social and intelligent animals. Goldfish feed voraciously and produce lots of waste. In this case, the tank requires an efficient filtration system to make aquarium water crystal clear and well oxygenation. Generally, the filtration system regularly filters the water and ensures the good water quality for your fish. If the filter does not produce the bubbles, you should use air pumps to ensure that the water is well oxygenated. The filter should be rinsed lightly in a bucket using tank water on a monthly basis or when it starts to get clogged up. In this case, avoid over-cleaning the filter media to retain beneficial bacteria. During the filtration process, beneficial bacteria break down the ammonia to less harmful nitrates and prevent poisoning the tank and fish mortalities. For creating tank environment healthy, tank inside should be cleaned to remove algae build up using safe algae scraper or with a magnetic glass cleaner. When cleaning an aquarium, you should never use detergents or any soap.

Goldfish should be kept in an aquarium with appropriate space. It should never be kept in bowls, small aquariums or any unfiltered container. An adult goldfish requires at least 10 gallons tank but larger is recommended. If you keep common goldfish, shubunkins and comets, at least 15-20 gallons tank per fish is required while adult fancy goldfish needs at least 10 gallons per one adult fish.

Goldfish require relatively high oxygenated water bodies. Some goldfish such as common goldfish, comets, and shubunkins grow to be quite large and make excellent outdoor pond fish. They are also known to survive relatively cold winters. Fancy goldfish (ornandas, ryukins, moors, and others) can also be kept in outdoor ponds.

The tank should not be decorated with sharp edges rocks which may rip fins, eye sacs of bubble eyes, moors, telescopes and celestial eyes. You should not use jagged or crushed glass gravel to prevent any injury because goldfish love to forage in the substrate. Generally, goldfish prefer to eat most live plants. In this case, you may use live plants like Cryptocorynes, Anubias and Java fern to make the natural environment and hiding spot. Generally, goldfish require sufficient plant cover to prevent stress. Roughly 50% of plants cover is recommended. Plants absorb waste products from the tank water and offer a healthy environment. Plants cover should be live plants with some artificial plants. You may also use driftwood and decorations for covering the aquarium. In this case, make sure all plants or decorations are safe for fish.

The aquarium should not be placed under direct sunlight or near windows to prevent algae outbreaks. For optimum growth of live aquarium plants, lighting should be provided for 8-10 hours a day.

Breeding Behavior

Goldfish are egg-layers and they can breed in captive condition with appropriate care. Goldfish species grow to sexual maturity with enough water and the right nutrition. Generally, they can reach sexual maturity when they become 4-7 inches in length. The breeding tank should be 20 gallons or larger is recommended. The breeding tank should have zooplankton, insect larvae, fish eggs, crustaceans and detritus as a natural fish food. Breeding usually occurs in spring or summer months after changing a significant temperature. Sexually mature males chase gravid female and help them to release their eggs.

Goldfish eggs are adhesive and they typically lay eggs on dense aquatic vegetations (Cabomba or Elodea ), a spawning mop or other decorations. After laying of eggs, the parents should be removed from the tank to prevent eating the eggs. Hatching of eggs occurs within 48 to 72 hours. The newly born baby turns into free swimming within a week and fry grows quickly to form its final shape. At this time, feed the fry with newly hatched Artemia or brine shrimp, infusoria or any liquid fry food. Feeding should be done 2-3 times a day for optimum growth. Within a year, the juvenile goldfish develop a mature goldfish color.

Sex Differences

Generally, sex differentiation between male and female is very hard. But during the breeding season, goldfish become brighter in colors. The belly of the female expands when she carry eggs in her belly while in the male pinhead-sized tubercles are seen on the operculum (gill covers), back and pectoral fins.

Goldfish Types

Over 300 different types of Goldfish are available in the pet fish market at a reasonable price. Here are some of the most popular goldfish, from them; you may pick and choose the right one for your aquarium.

• Bubble Eye Goldfish
• Celestial Goldfish
• Red Cap Oranda Goldfish
• Telescope Goldfish
• Veiltail Goldfish
• Black Moor Goldfish
• Red and white fantail goldfish
• Ryukin Goldfish
• Lionhead Goldfish
• Shubunkin Goldfish

Quick Goldfish Facts

Goldfish TypesOriginGrown-up sizeMinimum Tank SizeTemp
pHHardnessCare LevelLifespan
RyukinChina15.24 cm10 gallons65-78° F6.0-8.05-19 dGHEasy15 years or more
LionheadChina12.70 cm10 gallons65-78° F6.0-8.05-19 dGHMedium15 years or more
VeiltailUSA17.78 cm10 gallons65-72° F6.0-8.05-19 dGHMedium10-15 years or more
Telescope EyeChina20.32 cm10 gallons65-78° F6.0-8.05-19 dGHEasy10-15 years or more
Black moorChina10.16 cm10 gallons65-72° F6.0-8.05-19 dGHEasy15 years or more
Celestial EyeChina/Korea12.70 cm10 gallons65-78° F6.0-8.05-19 dGHMedium10-15 years or more
Bubble EyeChina12.70 cm10 gallons65-72° F6.0-8.05-19 dGHMedium15 years or more
Red Cap OrandaChina17.78 cm10 gallons65-72° F6.0-8.05-19 dGHEasy15 years or more
Red and white fantailChina15.24 cm10 gallons65-72° F6.5-7.55-19 dGHEasy15 years or more
ShubunkinChina/Japan30 cm10 gallons65-72° F6.0-8.05-19 dGHEasy20-25 years or more

Final Words

Goldfish are one of the most common and popular ornamental fish due to their brilliant body shape and colorations which make excellent pets for both experienced aquarium enthusiasts and new aquarium owners. It is inexpensive and readily available in the pet fish store with reasonable price. To keep goldfish healthy and happy in captive condition, you need the right place to live and right equipment such as filter, air pumps and balanced diet. As a pet fish lover, we recommend you to keep this gorgeous fish in your aquarium and make your home eye-catching to look.

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