Radioactive contaminants were detected in waters and fish in the ocean southeast of Fukushima, but that no impact on Chinese waters had been reported, China's maritime authority State Oceanic Administration said in a statement.
The latest data was collected via a 40-day monitoring of the Western Pacific Ocean conducted by the administration from April to June, state-run Xinhua news agency reported.
The administration has carried out regular monitoring of the ocean since the Fukushima nuclear accident in March 2011.
The plant suffered major damage from the 9.0-magnitude earthquake and tsunami that hit Japan.