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The Protection of the Miyako tanago

It is possible to breed the Miyako tanago in captivity, but only from the end of March until the first few days of July. As the spawning season approaches, the stomachs of the males turn red and signify that the time for mating has arrived. Also, as the stomachs of the females fill up with eggs, a transparent duct appears and undergoes a cycle of expansion and contraction. When this duct is fully expanded, this lets us know that it is now time for spawning. In a natural habitat, the female would skillfully lay her eggs inside the water duct of a bivalve and the sperm discharged from the male would find its way to the eggs inside the shellfish to complete the mating activity. But keeping the necessary bivalves inside an aquarium is extremely difficult. This makes successful breeding much more complicated. Spawning must be carried out artificially and everything from the insemination through incubation and feeding can only succeed in captivity with the aid of human hands.

The Miyako tanago struggle Document of a Birth


Petri dishes and beakers are treated with a 0.1% sodium chloride solution in order to prevent the formation of fresh water bacteria. Then special care is taken in the handling of the fish in order to avoid damaging the eggs.

Gathering the eggs

Eggs are carefully squeezed out from the expanded duct of the female. The eggs of the miyako tanago is a refreshing yellow color. After the insemination has taken place, the fertilized eggs are transferred into a beaker filled with a sodium chloride solution.


In their natural habitat, the eggs of the miyako tanago incubate inside a bivalve. Our manmade incubator assumes the role of the bivalves during the incubation period. Two days after insemination, the eggs hatch and the hatchlings start to swim.


The hatchlings are transferred from the incubator to the aquarium approximately 18 days after insemination. A staff member assumes responsibility for feeding them every three hours until they become able to fend for themselves.


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