A chemical leak that killed 4,400 fish in a Didcot stream is still being investigated.
The gudgeon, roach, dace and chub were discovered in Moor Ditch, north of the Ladygrove estate, at the end of July.
The Environment Agency (EA) said water samples indicated a cleaning chemical or detergent entered the waterway, but has now been flushed out.
Spokesman Narinder Sokhi said: “The chemical had been identified as a chemical related to cleaning but we do not know the source.”
If an individual or organisation is suspected of being responsible for the pollution, the agency could prosecute them.
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