[lxgr]

Where are you seeing Japan making that claim? From the article:

> The report noted that dead fish had begun washing ashore almost four months after the plant began discharging the water – which contains small quantities of the radioactive isotope tritium – into the Pacific.

> But no one has been able to confirm the cause. “The cause is unknown at the moment,” Mikine Fujiwara, a local fisheries official, told the newspaper. “We plan to sample the seawater at the site and examine it to uncover the cause.”