Koi Fish Beyond Ornament
In 2021, the famous Zouk otter family of Singapore broke into a church compound and, over the course of several days, ate nearly 100 koi fish. They left a messy trail of half-eaten bodies out of water. Otters
have also found their way into residential estates where there are koi fish ponds, and property owners have scrambled to put up gate modifications and pond covers to keep them out. The news coverage of these otter and koi incidents makes the human koi owners out to be victims of financial loss, but if we shift our focus, the koi are the ones experiencing real physical harm. They're admired for their beauty, celebrated in art and culture around the world, but rarely considered as creatures with their own inner worlds.
Koi fish, scientifically known as Cyprinus rubrofuscus, are closely related to goldfish. Like goldfish, they descend from the common carp, who are native to temperate regions of Europe and Asia. The common carp was first domesticated in China over 2,000 years ago, originally as a food source. In the 1800s, the Japanese began selectively breeding carp specifically for their colors, eventually creating the vibrant reds, oranges, whites, and blues we associate with koi today. The Niigata prefecture in Japan is where this all began, and it remains the gold standard for koi quality to this day. Beyond their beautiful scales, these fish are highly social, engage in a range of interesting interactions with humans, and have become deeply implicated in global trade.
Koi Sociality
Koi fish, and their carp ancestors, are intelligent and social animals. It is never recommended for koi fish to live alone, as isolated koi display greater anxiety-like behavior than those tested in pairs or groups. They display social hierarchy and variability. In the wild, carp are known to form distinct social groups, with individual carp maintaining associations with familiar fish in a study. When koi fish feel scared, they are observed to school together tightly to find strength and safety in numbers. One study found that having other koi around creates a social buffering effect, reducing the stressors for an individual koi fish. In a group, assertive leaders take initiative, guiding groups toward food or exploring new areas. Followers generally go along with whatever the dominant fish are doing, whereas peacemakers swim between aggressive group members to try and break up tension. Their deep sociality is all the more important when one considers that these fish live long lives. A koi can live from 25-50 years, but some have been reported to live up to 100 years. Their ancestors, the common carp, can live 15-20 years in the wild.
Jonathan Balcombe has a fascinating book, What a Fish Knows, that dives into the many complex ways in which fish communicate, including how koi—when trained—can not only distinguish between different genres of music but can even distinguish different composers from one another. While it is still unclear why these fish have such impressive auditory skills, it is clear that they are complex communicators. Fish like carp and koi also use chemical pheromones to communicate with one another and coordinate group behavior. For example, stressed koi will release alarm pheromones that will trigger others to avoid potential danger, and females will also release pheromones to attract potential mates during the spawning season. This sociality and capacity to communicate is likely one of the reasons for why carp were initially domesticated.
Needless to say, after so many generations of domestication, koi have become very attuned to humans and koi pond can be understood as an interspecies space where humans and fish are constantly reading and responding to each other.
Koi can recognize familiar human faces and voices, and research suggests they may even seek out positive interactions. In a 2021 study by researchers at New York University, koi who had become gradually accustomed to an experimenter consistently chose to swim close to them, and it was the koi who initiated touching the experimenter’s submerged hand. The researchers also noted that each koi displayed distinct personalities, with some frequently seeking tactile contact while others were more reserved. The researchers believe that these findings will have implications for fish welfare and ethics, suggesting that caring for fish should involve not only minimizing suffering but also providing opportunities for positive experiences.
While studies such as the above are interesting, and important, they remain rare. There has been very little scientific research on koi sociality, and what does exist, like with other domesticated animals, is often instrumentalist in focus, seeking to identify ways to better use, instead of understand, the animals.
Singapore’s Role in the Global Ornamental Fish Trade
Singapore's ornamental fish trade goes back to before the country's independence from the British in 1965, but it really took off afterward and into the present day.
By the 1990s, Singapore had become the world's leading exporter of ornamental fish, and by 2014, it accounted for nearly 20% of the global supply, with exports valued at around $69 million USD. The second largest exporter after Singapore is Japan, with its niche in koi fish exports. There are about 275 koi fish importers and exporters in Singapore, with imports coming primarily from Japan and exports being sent to places like the United States, which is the biggest importer of Koi fish in the world.
The koi farms in Singapore usually contain locally bred and Japanese imported Koi and because koi can only live in freshwater these farms are located in inland Singapore, usually in agricultural areas. Photos of these operations look like factory farms. The farms house anywhere from a few thousand to tens of thousands of koi who are separated into different pens based on their age and variety.
Koi farmers in Singapore have extensive networks within Southeast Asia. The lineage of most koi in Singapore can be traced back to Japanese stock, and along with the fish came entire systems of knowledge. While Singaporean koi breeders try to emulate the Japanese methods, moving koi from temperate Japan to tropical Singapore presented some challenges for koi hobbyists. At farms like the Max Koi Farm in Singapore, young fish that don't meet the exacting standards of high-quality Japanese koi—in terms of body shape, skin color, or skin smoothness—are culled. Furthermore, koi fish wellbeing also depends on specific environmental conditions, such as proper filtration, aeration, pH levels, and monitoring ammonia and nitrate levels, so their lives are entirely at the mercy of whoever controls these conditions.
The industry also struggles with disease. Over-intensive breeding has led to antibiotic resistance and outbreaks like Koi Herpes Virus and Spring Viraemia of Carp Virus. Biosecurity at serious koi farms is strict, as koi fish buyers have to change shoes and go through disinfection. But short-term biosecurity band-aids do not change the fact that fish still die in large numbers throughout the supply chain due to mishandling and disease. Koi fish may be valued highly as an expensive commodity and ornament, but in the business of breeding and trading these social, sentient beings, they can fall victim to tremendous disregard and suffering. In these cramped, stressful conditions, it is practically impossible for koi fish to practice their normal social behaviors and engage in complex group dynamics.
From 'Ornaments' to 'Invaders'
To circle back to the headline story of otters breaking into outdoor koi ponds, it’s important to remember that an outdoor pond is part of a larger ecosystem, where water is a shared resource and native predators like otters don't recognize the difference between a "wild" carp and a prized koi. To an otter or monitor lizard, a koi pond is simply an abundant fishing spot. In multispecies Singapore, the interactions between domesticated pet animals and wild animals can sometimes become contentious in public discourse. They bring into view the question of who really belongs to the city, based on their status. For example, in part due to their eating of koi fish, otters are considered for translocation and sterilization regimes to prevent them from living in certain areas.
There's also the issue of what happens when ornamental fish escape or get released. In Singapore, there are strict laws against the dumping of animals into waterways. “Ornamental species invasion” is the term for release into the environment that poses ecological and biodiversity threats.
A survey of Singapore’s reservoirs from 2010 showed that 90% of fish fauna documented were also encountered in the ornamental fish trade, 80% of which were likely released pet fish. To be an animal discarded from the ownership of humans and thrust into an unfamiliar wild means you are now considered an “alien,” villainized for threatening local biodiversity and spreading disease.
The pet fish industry’s overfishing of wild species has also jeopardized global fish diversity. Over 2,500 species of fish are caught up in the global ornamental fish trade, with about 60% coming from freshwater environments, and many of those are wild-caught. Wild populations of species like clownfish have been pushed toward collapse by aquarium demand. Of all the ornamental fish in the world, only 1% end up in public aquariums, with the other 99% going to private hobbyists.
Koi fish spaces in Singapore are prime examples of what Donna Haraway would call “contact zones,” realms where species interact, and false binaries break. Koi are agents of transnational relocations through the ornamental fish industry. Beyond the tranquility of the gardens they’re found in, this massive, global trade reduces these complex animals to ornamental objects and market value, which happens with all animals caught up in a hobby trade. Each fish typically sells for anywhere from $20 to a few hundred dollars, though premium specimens can sell for tens of thousands, and one record-breaking Japanese auction saw a single koi sell for $1.8 million USD.
Koi fish are the perfect example of how we symbolize, prize, and commodify animals. Koi fish are social, sensitive, intelligent animals with rich inner lives. Next time you stop to watch koi, notice their personalities and group dynamics, not just the beautiful colors of their body. Long celebrated as symbols of perseverance, koi have been forced to persevere both as a species caught up in a massive global trade and as individuals whose countless stories with humans reveal a relationship far more complex than the myths attached to them.
Of Interest:
Rebecca Shen a landscape designer, artist, and animal activist. She is inspired by design to advance interspecies justice and imagine more anti-speciesist spaces. Rebecca graduated with a Master in Landscape Architecture at Harvard Graduate School of Design in 2023. There, she completed her design thesis, Sanctuary State: California’s Cowscape in Transition, which envisions the transformation of an 800-acre industrial cattle feedlot into a cow sanctuary in the San Joaquin Valley. Rebecca contributes as an assistant content creator for the show.
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