Research and studies
Physical measurements of a Whale shark were taken
October 31, 2025
Ahead of Measurement Day on Saturday, November 1st, the total length and girth of the Whale shark on display in the Pacific Ocean tank were measured on Friday, October 31st.
The results are as follows:
| full length | girth | Estimated weight | Estimated Age | |
|---|---|---|---|---|
| Kai (male) | 5 m 30 cm Last year (4 m 70 cm) |
2 m 60 cm Last year (2 m 30 cm) |
1,100 kg Last year (700 kg) |
8-9 years old |
| Yuu (female) | 6 m 20 cm Last year (6 m 20 cm) |
2 m 70 cm Last year (2 m 60 cm) |
1,800 kg Last year (1,800 kg) |
18-19 years old |
Since its arrival on October 2nd last year, Kai has grown by 60 cm in length and is estimated to weigh 400 kg.
Yuu's overall length has not changed, but her girth has increased by 10 cm. Because weight is estimated from overall length, her estimated weight is the same as last year, but it is highly likely that he has gained weight.
At Kaiyukan, we regularly measure the body of Whale shark as part of our health management and ecological research into their behavior, the details of which are still unknown. A aquarium keeper took a tape measure to the whale Whale shark while it was eating in tank , measuring its overall length and girth to calculate its estimated weight.
Through the Measurement Day, we hope to showcase the healthy growth of living creatures and to raise awareness of Kaiyukan's health management efforts and the natural environment.
Check out this creature's blog too!
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[Limited Time Only] Baby Barrier reef chromis on Display
Baby Barrier reef chromis, a species of damselfish endemic to the Great Barrier Reef, the world's largest coral reef, are on display for a limited time at the aquarium keeper counter on the 4th floor of the entrance building. These babies were hatched in the tank after the Great Barrier Reef tank was renovated, with the eggs laid by the parent fish being collected by the aquarium keeper. Although still small, they have grown to the point where their distinctive features, such as their yellow heads and the black stripe running from their eyes to their dorsal fins, are clearly visible. You can also watch aquarium keeper explain the species and feed them daily from 1:10 PM to around 2:00 PM. Information about the breeding behavior of Barrier reef chromis and other damselfish species is also available on the blog "Behind the Scenes at Kaiyukan ." Period: February 20, 2026 - April 20, 2026 (tentative) Location: aquarium keeper Counter, 4th Floor, Kaiyukan Entrance Building *The exhibition may be suddenly canceled depending on the condition of the animals. Barrier reef chromis ( English name: Barrier reef chromis, scientific name: Chromis nitida) is a species endemic to the Great Barrier Reef. Among damselfish, which are generally territorial and aggressive, it has a relatively gentle temperament.