Japan’s koi breeders lost their biggest export market after China did not renew the licences it had awarded to numerous farms there.

The last of the licences expired in October 2023, and the Chinese authorities did not offer an explanation for the non-renewals, according to media reports.

In the past, China had awarded licences – valid for three years – to 15 farms in Japan, reported The Asahi Shimbun daily on Dec 8.

“We have heard no explanations from the Chinese side on the latest development,” a Japanese government official was quoted by the newspaper as saying.

“It appears more likely than not, however, that China is harassing us over the release of treated water.”

In 2023, Japan released treated water from the Fukushima nuclear plant into the Pacific Ocean, and it will continue to do so in phases over the next few decades.

A 2011 tsunami had ravaged the area, and more than a million tonnes of treated water were stored in the plant before the 2023 water release.

Adorned with beautiful colours and patterns, koi are popular pets that have been described as swimming jewels.

A single fish can sell for hundreds of thousands of yen, and prices may yet skyrocket, according to the Japanese media.

In 2018, a koi was sold for about 200 million yen (S$1.9 million) to a Taiwanese buyer.

Japan’s koi exports had doubled over the past 10 years to 6.3 billion yen, according to The Associated Press. About a fifth of the exports were for China – the single biggest importer of the fish from Japan.

Japan is seeking new export channels in Europe and South-east Asia. However, a farm official said that this amount cannot compensate for the loss of exports to China.

Japanese officials said Tokyo had handed in documents to renew koi export licences and will tap diplomacy to address the export issue, reported The Associated Press on Nov 11.