Quick Answer
Koi swim in the street canals of Shimabara, Japan, because the water isn’t wastewater at all — it’s clean spring water. In 1792, the Unzen-Mayuyama disaster (Japan’s deadliest volcanic catastrophe, killing roughly 15,000 people) fractured the ground and created over 60 natural springs throughout the city. Nearly two centuries later, in 1978, residents of the Shinmachi neighborhood released koi into a 100-meter spring-fed canal, turning tragedy into one of Japan’s most charming tourist attractions — now nicknamed “Koi no Oyogu Machi,” the City of Swimming Carp.
Why Koi Fish Swim in Japan’s Street Gutters!
Have you ever stumbled upon videos or photos of koi fish gracefully swimming in the street gutters of Japan and wondered why they are there? It might seem like these vibrant fish are thriving in super clean wastewater channels, but the truth is far more fascinating and rooted in history. Let’s dive into the unique story of Shimabara, a city where a natural disaster centuries ago set the stage for koi fish to become a charming and beloved part of the urban landscape.
The Curious Case of Koi in Street Gutters
Koi fish are typically associated with serene ponds and carefully maintained gardens. So, seeing them in street gutters naturally raises questions. Contrary to popular belief, these koi aren’t swimming in ordinary wastewater. Instead, they inhabit special clean canals that run through the city, fed directly by natural springs — not connected to any sewage or drainage system at all. The water is so pure that it’s genuinely one of the defining features of the city, which has earned the nickname “City of Water” thanks to more than 60 known springs scattered throughout Shimabara.
Shimabara’s Natural Springs: A Gift from Disaster
The story begins specifically on May 21, 1792, when Shimabara was struck by what’s now known as the Unzen-Mayuyama disaster — a catastrophic landslide triggered by volcanic activity at Mount Unzen, followed by a massive tsunami. The disaster killed approximately 15,000 people, making it the deadliest volcanic disaster in Japanese history. While utterly tragic, the same geological upheaval fractured the ground and created dozens of fresh natural springs across the area — springs that still flow today, providing the city with a steady, genuinely pristine source of water more than two centuries later.
From Disaster to Delight: The Birth of Shimabara’s Koi Canals
Fast forward to July 1978 — residents of the Shinmachi neighborhood decided to embrace this natural gift in a creative way. To beautify public spaces and add a touch of life and color to the city, they released colorful koi into a 100-meter stretch of the clean, spring-fed canal running through their neighborhood. The initiative was such a success that more residents and local authorities joined in over time, releasing additional koi and extending the practice throughout the city. Today, hundreds of koi swim in these canals, with some growing up to roughly 70 centimeters long — and the area has earned the nickname “Koi no Oyogu Machi” (the City of Swimming Carp), drawing nearly 94,000 visitors in a single year.
📷 Japan Travel Photo Book: Gardens, Scenic Views & Landmarks
A beautiful coffee table collection of Japan’s most scenic destinations — a nice way to keep exploring places like Shimabara from home, or plan your own visit.
🛒 Check Price on Amazon →Why This Matters: More Than Just Beauty
The presence of koi fish swimming in Shimabara’s street gutters is not just a quirky visual. It’s a genuine testament to how communities can turn adversity into opportunity. The fresh springs, born from a natural disaster that claimed thousands of lives, were repurposed nearly two centuries later to enhance urban life and foster a real connection between people and nature. The koi fish genuinely symbolize resilience and beauty emerging from hardship, enriching Shimabara’s charm and identity as a destination worth visiting.
Conclusion: The Charm of Shimabara’s Koi Fish
Next time you see koi fish swimming in Japan’s street gutters, remember that it’s not about unusually clean wastewater but a remarkable historical and environmental story spanning more than two centuries — from a deadly volcanic disaster in 1792 to a community’s creative vision in 1978. Shimabara’s koi-filled canals are a living legacy of nature’s power and human creativity. If you’re fascinated by unique stories like this, Shimabara is definitely worth adding to your Japan travel list — not just for its koi fish, but for the genuinely inspiring tale they represent.
FAQs
What disaster created Shimabara’s springs?
The 1792 Unzen-Mayuyama disaster — a volcanic landslide and tsunami that killed approximately 15,000 people, making it Japan’s deadliest volcanic disaster. The same geological event created the springs that still flow through the city today.
When were koi first released into Shimabara’s canals?
In July 1978, when residents of the Shinmachi neighborhood released koi into a 100-meter stretch of spring-fed canal.
Is the water in Shimabara’s street canals actually clean?
Yes — it’s genuine natural spring water, not wastewater or drainage. Shimabara has more than 60 known springs and is nicknamed the “City of Water.”
How big do the koi in Shimabara’s canals get?
Some grow to roughly 70 centimeters (about 27-28 inches) long.
You may also like
Passionate about fish keeping since elementary school in the 1980s, Giovanni Carlo has dedicated countless hours to collecting and breeding a diverse array of ornamental freshwater fish. From vibrant guppies and majestic koi to striking bettas and classic goldfish, he continues to explore the fascinating world of aquatics, sharing knowledge and enthusiasm with fellow fish enthusiasts.