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The Oldest Fish in History

Koi fish in a beautiful pond
Image created by Animals Around the Globe using DALL-E

The oldest koi fish in History lived in a Japanese family’s pond. This beautiful scarlet-hued koi fish was named Hanako, which means ‘flower child’. It has been claimed that she was born 25 years before the Declaration of Independence in Japan. She peacefully departed this world when she was around 226 years old, claiming her title as the world’s oldest fish.

Koi head closeup
Koi head closeup. By Stan Shebs, CC BY-SA 3.0,

Delving into the Mysteries 

Koi fish. By Bernard Spragg. NZ from Christchurch, New Zealand – Koi Carp., CC0,

The story of Hanako has fascinated generations of people, yet skepticism surrounds her reported age. No official historical records or concrete scientific evidence validates Hanako’s age. National Geographic has acknowledged the possibility that Hanako’s saga might only be a captivating legend.

A Tale Transcending Time 

Koi fish is domesticated version of common carp.
Koi fish is domesticated version of common carp. By Bernard Spragg. NZ from Christchurch, New Zealand – Koi carp., PDM-owner,

The story of Hanako started in 1966, when Komei Koshihara, a custodian of this respected fish, shared enchanting anecdotes of their bond on Japan’s Nippon Hoso Kyokai radio station. At this point in time, Hanako weighed 7.5 kg and measured 70 cm in length. Koshihara affectionately described Hanako’s demeanor and recounted moments of connection that seemed to transcend the barriers between man and fish. 

How Was This Koi Fish’s Age Determined? 

Three Koi Fish
By Tubifex – Own work, CC BY-SA 3.0,

A former professor at the Laboratory of Animal Science at Nagoya Women’s University, Mayaoshi Hiro, determined the age of the fish through the analysis of her scales. While this method is commonly used to determine the age of fish, the process was not peer-reviewed; thus, there are doubts about its accuracy.

Unraveling the Identity of Japan’s Beloved Koi

Several varieties of koi carps in the Japanese Garden of Montreal Botanical Garden, Canada.
Several varieties of koi carps in the Japanese Garden of Montreal Botanical Garden, Canada. By Marc-Lautenbacher – Own work, CC BY-SA 4.0,

The species of Hanako remains a mystery. However, some suggests she may belong to either of two prominent species of koi fish: Cyprinus rubrofuscus or Cyprinus carpio. Hanako’s age defies conventional expectations for these koi species. Koi, known for their resilience and endurance, typically boast lifespans averaging approximately 40 years. 

Validation Amidst Doubt 

Koi fish
By Vladimir Menkov – Own work, CC BY-SA 3.0,

The Smithsonian National Zoo and Conservation Biology Institute provided a glimmer of validation by reporting the existence of a koi fish that was almost 230 years old, affirming the plausibility of Hanako’s remarkable age. However, the lack of a specific reference to Hanako’s name leaves room for skepticism. The methodology used to ascertain Hanako’s age comes under scrutiny, with experts suggesting that scales might not be the most precise means of measurement. 

Seeking Clarity 

By Vladimir Menkov – Own work, CC BY-SA 3.0,

A report shared in the Review in Fish Biology and Fisheries advocates for more rigorous protocols in fish aging methodologies, suggesting that current practices may not be accurate or consistent. It emphasizes the importance of validation and precise terminology. Such scrutiny underscores the complexity of determining the age of creatures like Hanako and urges caution against accepting claims without meticulous examination. 


By I, Jmabel, CC BY-SA 3.0,

Hanako’s story is a captivating mystery. Whether a legendary symbol of resilience or a product of embellished folklore, her legacy endures.

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