This Tokyo Pond Contains Fish From Space

Your Guide to the World's Hidden Wonders
Feb. 10 2014 12:42 PM

Tokyo's Roppongi Hills Garden is Home to Extraterrestrial Fish

Atlas Obscura on Slate is a blog about the world's hidden wonders. Like us on Facebook, Tumblr, or follow us on Twitter @atlasobscura.

When office workers at the 54-story Mori Tower in the Roppongi Hills urban community need some fresh air, they head downstairs to Mohri Garden. The tranquil green space contains a pond that was once part of a 17th-century feudal estate. Now, the pond is home to thousands of Medaka fish with an unusual pedigree: they are the descendants of fish who were born in space.

In July 1994, four Medaka — a hardy, inch-long species found in lakes and rice paddies around Japan — traveled to space aboard the NASA shuttle Columbia. During the 15-day voyage, scientists observed the breeding of the Medaka to see if the microgravity environment would affect their behavior. The fish mated and their eggs hatched normally, giving the four adult Medaka the distinction of being the first vertebrates to mate while orbiting Earth.


When the shuttle returned, the offspring of the astronaut fish spent a few months being studied in a Japanese lab before being distributed to "foster parents" at schools, museums, and homes across the country. In 2003, the Roppongi Hills complex opened, boasting four apartment buildings, a corporate high-rise, museums, hotels, and a shopping center. During a welcoming ceremony involving 1,000 school children, Japanese astronaut Mamoru Mohri released 10,000 descendents of the extraterrestrial fish into the garden pond.

With a lifespan of three to five years and a breeding age of seven weeks, the Medaka of Roppongi Hills have thrived. Meanwhile, aboard the International Space Station, microgravity experiments on their species continue.

The Mohri Garden pond by day...

Photo: machu/Creative Commons

Something fishy's going on here:

View Roppongi Hills in a larger map


Medical Examiner

The Most Terrifying Thing About Ebola 

The disease threatens humanity by preying on humanity.

I Bought the Huge iPhone. I’m Already Thinking of Returning It.

Scotland Is Just the Beginning. Expect More Political Earthquakes in Europe.

Students Aren’t Going to College Football Games as Much Anymore

And schools are getting worried.

Global Marches Demand Action on Climate Change


Blacks Don’t Have a Corporal Punishment Problem

Americans do. But when blacks exhibit the same behaviors as others, it becomes part of a greater black pathology. 

Why a Sketch of Chelsea Manning Is Stirring Up Controversy

How Worried Should Poland, the Baltic States, and Georgia Be About a Russian Invasion?

  News & Politics
Sept. 20 2014 11:13 AM -30-
Business Insider
Sept. 20 2014 6:30 AM The Man Making Bill Gates Richer
Sept. 20 2014 7:27 AM How Do Plants Grow Aboard the International Space Station?
  Double X
The XX Factor
Sept. 19 2014 4:58 PM Steubenville Gets the Lifetime Treatment (And a Cheerleader Erupts Into Flames)
  Slate Plus
Tv Club
Sept. 21 2014 1:15 PM The Slate Doctor Who Podcast: Episode 5  A spoiler-filled discussion of "Time Heist."
Sept. 21 2014 9:00 PM Attractive People Being Funny While Doing Amusing and Sometimes Romantic Things Don’t dismiss it. Friends was a truly great show.
Future Tense
Sept. 19 2014 6:31 PM The One Big Problem With the Enormous New iPhone
  Health & Science
Bad Astronomy
Sept. 21 2014 8:00 AM An Astronaut’s Guided Video Tour of Earth
Sports Nut
Sept. 18 2014 11:42 AM Grandmaster Clash One of the most amazing feats in chess history just happened, and no one noticed.