Goldfish

Quick Take

• The tiny fish in your bowl could grow into something you'd never expect. Goldfish have a hidden size potential most owners never see. Discover their true size →
• Goldfish aren't born gold, and the reason behind their color change reveals something fascinating about the species. See how color evolved →
• A goldfish's lifespan can shatter everything you thought you knew about keeping them as pets. Explore their real lifespan →
• Goldfish have a hidden anatomical feature that puts them in a completely different category from what most people picture. See their true classification →

People started breeding goldfish of different colors in China 1,000 years ago. Only members of the imperial Song dynasty were allowed to own the gold or yellow variety, as yellow was the imperial color.

Once thought fit only for emperors, the goldfish has become a well-loved pet. Intelligent, curious, and beautiful, it is hardy and long-lived.

Classification and Scientific Name

Goldfish belong to the Cyprinidae family and the Carassius genus, and the scientific name is Carassius auratus. Carassius is derived from the Latin word carass, which is a name for the fish. Auratus means “gilded.”

Biologists used to believe the goldfish was a subspecies of the crucian or Prussian carp, but it is now considered a distinct species.

Though there is only one species of goldfish, there are countless breeds.

Appearance

The look of your “common” goldfish is unmistakable. First and foremost, it is a brilliant coppery gold color found on no other fish. Those kept as pets usually grow no longer than 3 inches, but they can grow to over 16 inches in size and weigh over 9 pounds.

The body can be torpedo-shaped or egg-shaped, but what most goldfish share are a pair of pectoral fins, a pair of pelvic fins, one dorsal fin, one anal fin, and one caudal or tail fin.

Their lateral lines, which help them sense pressure, movement, and vibrations in the water, bear 25 to 31 scales, but they do not have scales on their heads. They have large eyes, and their sense of smell and hearing are highly developed.

Different breeds can have bubble or telescope eyes, veils, butterfly or fan-shaped tails, heads resembling raspberries, and scales resembling rows of pearls. They can come in the usual gold as well as combinations of black, white, purple, red, brown, or yellow.

Evolution and Origins

Goldfish (Carassius auratus), which were originally domesticated in ancient China, are actually derived from crucian carp, and both are still classified as the same species. Crucian carp hold significant agricultural value, with a worldwide aquaculture production of approximately 1.7 million tons in the early 2000s, with recent estimates remaining below 2 million tons.

During the Jin and Tang Dynasties (265–907 AD) in ancient China, selective breeding of normally gray or silver carp began. During this process, a color mutation emerged, leading to goldfish with yellow-orange scales.

The evolutionary origins of goldfish remain unclear, but past research has suggested that they may have originated from a wild population of crucian carp. It has been theorized that red and yellow variations of goldfish emerged through natural mutations within the wild crucian carp population.

Different Types

Here are the different types of goldfish:

• Oranda
• Ranchu
• Common goldfish
• Fantail
• Comet
• Black Moor
• Shubunkin
• Ryukin
• Telescope
• Lionhead
• Pearlscale
• Bubble Eye
• Butterfly telescope goldfish
• Panda Telescope
• Wakin

Distribution, Population, and Habitat

C. auratus is native to China, but it has spread all over the world, either as a pet or an escapee into freshwater bodies. It is a tough, long-lived fish that prefers cold water and tolerates turbid conditions. Besides tanks and bowls, they can be found in pools, ponds, slow rivers, canals, and even drainage ditches.

Predators and Prey

Goldfish are omnivores, and their food includes plant material and small animals such as mosquito larvae and brine shrimp. They actually have teeth in their throat, called pharyngeal teeth, which help them grind up their food.

In turn, they fall prey to any animal that preys on fish. These include turtles, waterbirds such as herons and gulls, as well as other, larger fish such as pike.

Reproduction and Lifespan

Goldfish reproduce if their tank has the right maintenance and if they are given the proper care. In the wild, they start to breed in the spring. Females grow fat with unfertilized eggs, and males chase them around and prod them until they release their eggs.

Then, the male fertilizes them. The eggs are sticky and cling to the leaves of aquatic plants or rocks. They hatch after two to three days.

The baby fish or fry are brown at first, and it may be as long as two to three months before they take on the glittering gold of their species. Still, they grow very quickly to avoid being eaten. Predators may include other adult goldfish of the same species. A pet goldfish typically lives 10 to 15 years, and the oldest recorded goldfish lived to 43 years in captivity.

Fishing and Cooking

Though C. auratus is a type of carp and is perfectly edible, it’s not used in cooking unless a fisherman happens to land an unusually large one. In 1939, goldfish swallowing was a fad. Fortunately, it fell out of favor, though it is still practiced here and there.

Population

While there is no precise global population estimate, goldfish are widespread and can become invasive pests when released into the wild. Large populations of goldfish, numbering in the thousands, have been documented in areas such as Hamilton Harbour in Lake Ontario.