Fish stocks on the stretch of a Staffordshire river polluted with a deadly chemical and raw sewage have been wiped out, say scientists.
A survey along 700m of the River Trent found almost no evidence of living fish, say the Environment Agency.
But fish stocks a few miles further downstream seemed to be mainly unaffected by pollution, reports found.
More tests are being carried out on river life to work out exactly how much damage the leak on 6 October caused.
Thousands of fish between Stoke-on-Trent and the village of Yoxall died as a result of the chemical cyanide and untreated sewage leaking into the water.
Environment officers were able reduce pollution levels in the river by pumping oxygen into the water.
At the time, farmers, anglers and boaters are being warned that water should not be taken out of the river "for any reason".