Japan's fisheries agency said on Saturday fish tested in waters around the wrecked Fukushima nuclear plant did not contain detectable levels of the radioactive isotope tritium, Kyodo news service reported.
Nets were set up on Thursday when plant operator Tokyo Electric Power Company (Tepco) 9501.T began releasing treated radioactive water into the Pacific, angering fishermen and many others in Japan, alarming consumers in neighbouring countries and prompting China to ban Japanese aquatic products.
The agency plans to announce test results daily. Tepco said on Friday seawater near the plant contained less than 10 becquerels of tritium per litre, below its self-imposed limit of 700 becquerels and far below the World Health Organization's limit of 10,000 becquerels for drinking water.
Calls to the fisheries agency for comment were not answered on Saturday.
After a lengthy debate, the government of Prime Minister Fumio Kishida decided on Tuesday to allow the release of 1.3 million tons of treated water from the Fukushima plant, destroyed by a 2011 tsunami because Tepco was running out of storage space.
The utility filters most radioactive elements out of the water but dilutes tritium, an isotope of hydrogen, which is difficult to separate from water.
A Ukrainian F-16 fighter pilot died in a crash while repelling a Russian air attack that involved hundreds of drones, cruise and ballistic missiles, authorities said on Sunday, as Moscow intensifies night-time air barrages in the fourth year of war.
Two firefighters were shot dead while responding to a fire in northern Idaho and the body of a man was later found with a gun nearby, the Kootenai County Sheriff's Office said on Sunday, as it lifted a shelter-in-place order.
Iran could be producing enriched uranium in a few months, the head of the UN nuclear watchdog Rafael Grossi was quoted as saying on Sunday, raising doubts about how effective US strikes to destroy Tehran's nuclear programme have been.
The Jerusalem District Court has cancelled this week's hearings in Prime Minister Benjamin Netanyahu's long-running corruption trial, accepting a request the Israeli leader made citing classified diplomatic and security grounds.
The Israeli military ordered Palestinians to evacuate areas in northern Gaza on Sunday before intensified fighting against Hamas, as US President Donald Trump called for an end to the war amid renewed efforts to broker a ceasefire.