Weedy Seadragon is a large pipefish species that can grow to over 45 cm in length and inhabits the waters around southern Australia and Kawakawa.


As is typical of the Syngnathidae family, the female lays her eggs on the male's tail. During the breeding season, a spongy brood pouch develops on the ventral side of the male's tail, where the female lays her eggs. The male then continues to guard the eggs until the larvae hatch. Their numbers are declining in their natural habitat, making them a protected species, and many aquariums around the world are working to conserve and breed them, making them an extremely rare fish.

At Tokyo Sea Life Park, since its opening, females have laid eggs, but the eggs have fallen off without being attached to the males, and have not hatched. In 1993, a male laid eggs, the first in the world, and hatching was observed, but the aquarium was not successful in raising the offspring.

We learned that synchronizing the timing of the male and female's breeding behavior is crucial for successful reproduction, so from a young age, we adjusted the water temperature and day length of the breeding environment to match their natural habitat to encourage sexual maturity. Furthermore, using the information we gathered, we prepared a dedicated tank for Weedy Seadragon and attempted to breed them, resulting in spawning in 2019.

I was fortunate enough to have the opportunity to actually observe a male seadragon with eggs attached to its tail, something I had only ever seen in videos before, and I was also able to record the long-awaited moment of hatching on video. This video recording allowed me to actually see the male Weedy Seadragon shaking its body violently all night long as the larvae slowly hatched one by one.

And now, we have successfully raised the hatched fry. In recognition of this achievement, we have been awarded the "First Breeding Certification" by Japanese Association of Zoos and Aquariums Association of Zoos and Aquariums. The First Breeding Certification is a system that recognizes the first successful breeding among the member facilities of Japanese Association of Zoos and Aquariums Association of Zoos and Aquariums (this is the successor to the previous breeding award).

Tokyo Sea Life Park has been working on breeding various organisms for a long time. Including previous breeding awards, this is our 53rd certification. Encouraged by this achievement, we will continue to work on breeding various organisms in the future.

Related videos
"The Birth of Weedy Seadragon (Tokyo Zoo Net BB)
"Weedy Seadragon that mimic seaweed (Tokyo Zoo Net BB)

[Tokyo Sea Life Park]

(March 19, 2021)