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.
The US and Iran failed to reach an agreement to end their war despite marathon talks that concluded on Sunday in the Pakistani capital Islamabad, jeopardising a fragile ceasefire.
At least 30 people were killed on Saturday in a stampede at the Laferriere Citadel in the northern countryside of Haiti, authorities said, warning that the death toll could rise.
A cyclone battered New Zealand's North Island on Sunday, cutting power to thousands of residents and forcing hundreds to evacuate, as officials warned conditions would worsen through the day.
Negotiations between the United States and Iran appeared to have concluded for now, Iran's government has announced early on Sunday, after a series of talks in Pakistan to end the six-week war between Washington and Tehran.
Costa Rica on Saturday has received the first group of migrants from other countries deported from the United States under an agreement signed in March between the two countries, local authorities said.