Science & Tech · Science & Environment · 3 hrs ago
Nara students find medaka can voluntarily dive more than 10 meters
Three students at Unebi Senior High School in Kashihara, Japan, tested how deep medaka can dive in a specially built tank.
Medaka are small freshwater fish commonly found in Japan and are usually seen in shallow ponds and streams.
The students placed 12 fish in a transparent tank that was 10.66 meters deep; two fish caught in a nearby waterway swam close to the bottom.
A professor who helped with the project said this is believed to be the first experimental observation of medaka voluntarily diving beyond 10 meters.
Earlier studies showed the fish can withstand pressure found at about 500 meters underwater, but did not establish how deep they choose to swim.
The finding raises questions about why medaka usually live in shallow water, and the students and professor want to investigate why some fish dived while others did not.
Nara high school students found that two medaka voluntarily descended to near the bottom of a 10.66-meter tank.
The experiment took place at Unebi Senior High School in Kashihara, Nara Prefecture, on Oct. 17, 2026.
The students tested 12 medaka in a transparent, tube-shaped aquarium about 7 centimeters in diameter.
A collaborating professor said the observation is believed to be the first experimental record of medaka voluntarily diving more than 10 meters.
The students and professor said they want to investigate why some fish dived deeper than others.
- Who
- Three second-year male students at Unebi Senior High School conducted the experiment.
- What
- They observed two medaka voluntarily descend to near the bottom of a 10.66-meter tank.
- When
- Oct. 17, 2026.
- Where
- Unebi Senior High School in Kashihara, Nara Prefecture, Japan.
- Why
- The students extended an earlier experiment to study how deep medaka would voluntarily dive.
This story does not have two clearly opposing sides.
Fukamachi conducted several experiments on a university campus, increasing the water depth in stages until most fish descended to the bottom of a 9-meter tank.
Unebi Senior High School students tested 12 medaka in a 10.66-meter tank, and two descended to near the bottom.
- Fish tested
- 12 medaka
- Tank depth
- 10.66 meters
- Tank diameter
- About 7 centimeters
- Fish reaching near the bottom
- 2
- Experiment location
- Unebi Senior High School, Kashihara, Nara Prefecture
What people are saying
I wanted a guideline based on the idea that medaka do not dive deep, meaning that searching shallow areas would be sufficient.
I'm curious why some of the fish dived while others did not. I'd like to conduct further experiments to find out.
If they (medaka) can dive this deep, I wonder why they live in shallow water instead of venturing into deeper parts of rivers. Since only two fish made it all the way to the bottom, I'd like to conduct further experiments to find out more.