In the lives of residents in inland areas, the most familiar fish is perhaps the goldfish. This colorful ornamental fish can beautify any room in your home. However, if you try to find this fish in nature, you may face continuous disappointments, as they are a man-made species. This artificial nature has led to many characteristics of the original fish being lost in goldfish, which is also why, even if released into the wild, they cannot survive.
In reality, from food types to pets, few organisms have been as thoroughly transformed by humans as the goldfish. They have been selectively bred for centuries solely to fulfill our desires, preferences, and imaginations. From the plain and dull fish of the past, they have evolved into vibrant creatures with diverse body shapes, even deformities.
This colorful ornamental fish can beautify any room in your home.
Many believe that the ancestor of the goldfish is the carp or koi; however, the only common trait they share is their docility. In fact, the ancestor of the goldfish is the wild crucian carp.
From 1928 to 1934, Professor Chen Zhen in China discovered a truth in his experiments on goldfish breeding: any type of goldfish can be crossbred with wild crucian carp and produce fertile offspring. This experiment first demonstrated that there is no reproductive isolation between goldfish and crucian carp, and they are closely related. Subsequently, scientists conducted further studies comparing embryonic development and analyzing karyotypes to show that goldfish originally came from Chinese crucian carp. Taxonomically, goldfish are not a separate species; rather, they are classified within the same species as crucian carp (Carassius auratus).
Crucian carp
So what factors led to the transformation of crucian carp into goldfish? The answer lies in the evolutionary process: “gene mutation, natural selection,” while the evolution of goldfish is characterized by “gene mutation, artificial selection.” This process is quite similar to typical dog breeding; however, the breeding and selection of goldfish by humans has been more extreme. After centuries of selection by the Chinese, goldfish lost all the physical traits of crucian carp. From body color, body shape, head shape, eye shape, scales, back, tail, to anal fins, they have fundamentally changed and appear completely different from crucian carp.
The most primitive mutation in the evolution from crucian carp to goldfish occurred in body color. Among countless ordinary crucian carp, occasionally a strikingly colored golden crucian carp would appear. According to existing historical data, the earliest record of these mutated fish dates back to the Jin Dynasty in China (265-420 AD), around 1,600 years ago.
Crucian carp and goldfish.
However, at that time, people believed these fish were special and might be related to spiritual factors; therefore, whenever they caught one, they would often release it back into the water, considering it a virtuous act that would benefit their descendants. By the Tang Dynasty, this practice continued, but now, people built specific release ponds (which also contained other creatures like turtles and golden crucian carp), into which accidentally caught golden crucian carp from nature were released, creating semi-domesticated individuals.
By the Song Dynasty, officials of the Chinese court began to breed goldfish artificially.
Over time, people began to build ponds specifically for breeding goldfish and crucian carp for recreational purposes and ornamental enjoyment. It wasn’t until the Song Dynasty that officials of the Chinese court began to breed goldfish artificially. From then on, some dignitaries also imitated this, establishing their own gardens with fish ponds to enjoy watching the fish. Wild crucian carp thus entered a state of domestication. To avoid hybridization with natural crucian carp in the ponds, they selectively bred fish with three colors: yellow, silver-white, and light green.
Of course, not everyone had the ability to breed fish in a large pond. Ordinary people wanting to keep up with the trend started making bowls and tanks to breed goldfish on a larger scale. By the Jiajing era of the Ming Dynasty (1546), private goldfish breeding had become very popular.
This was, in fact, the most significant turning point in the history of goldfish domestication. The shape of the goldfish underwent tremendous changes from this point onward. Due to the pressures of living in bowls, the physique of goldfish also changed, indirectly affecting their genetics through artificial selection.
The shape of the goldfish has undergone tremendous changes since that time.
In nature, to swim quickly to avoid predators or find food, the body shape of fish is generally elongated. However, in small tanks, the mobility space of goldfish is restricted to an unprecedented extent, which is why they can only swim slowly. Under human protection, they not only avoid the pursuit of natural enemies but also increasingly rely on artificial food sources. As a result, the new genetic variations are more likely to be preserved under the careful care of humans.
At that time, ancient people understood how to deliberately select and breed individuals that adapted to life in small tanks and bowls. This artificial selection also accelerated the evolution of the entire body of goldfish, leading to the formation of many different new varieties.
The shape of goldfish changes over time.
In just a few hundred years, the elongated shape suitable for fast swimming has transformed into a short, rounded shape. The originally straight, single tail has also evolved into long and wide forked tails, with some fin tails becoming multi-lobed; some having bubble-like protrusions; some with large head tumors on top … Darwin, in his book “The Variation of Animals and Plants Under Domestication“, described that there were “no less than 89 varieties” in China at that time.
After the Qing Dynasty, fish farmers with a business mindset began to consciously engage in artificial breeding and directed the breeding of goldfish. During this golden age, goldfish were also introduced to Japan in waves and later to European countries by the late 19th century. Virtually all goldfish breeds worldwide today trace their origins back to China. Therefore, goldfish are also nicknamed “the sacred fish of the East.”
Goldfish are nicknamed “the sacred fish of the East.”
Currently, there are over 300 varieties of goldfish in China. Although some characteristics, such as body color, are neither beneficial nor harmful for survival, it is not difficult to see that the vast majority of mutated goldfish lack the ability to survive in nature.
For example, the short, round body shape and various unusual tail shapes do not benefit goldfish swimming abilities. Among them, tail type variations are divided into nearly a dozen types, including single tails, double tails, single tails on double tails (three tails), standing tails, fan tails, butterfly tails …
The absence of a dorsal fin, a characteristic feature of the egg-shaped goldfish, makes it easy for them to lose balance and become disoriented when swimming too vigorously.
The plump, short body makes them prone to swim bladder disease and increases their mortality rate.
Various head tumor forms, which are essentially a thin layer of epithelial cells that continuously divide and proliferate, contain loose connective tissue and mucus. However, whether it is a high head, dragon head, tiger head, lion head, or goose head … all are “burdens” for the head and gill cover, affecting the respiration process of goldfish. As a result, they cannot withstand the impact of strong currents.
Various head tumor forms, which are essentially a thin layer of epithelial cells.
With careful human care, these peculiar deformities will not affect the survival of goldfish. They simply need to remain quietly underwater; aside from eating and swimming, their genes can be preserved and passed down from generation to generation. Goldfish are bred to bring happiness to people, and in return, humans provide them with a “superior” life compared to their wild counterparts. However, many goldfish exhibit excessive bodily mutations, making them prone to sudden death. Humans are always in search of the new, which raises questions about the future of goldfish and the changes that lie ahead—perhaps few can accurately predict what will come.
