The Environment Agency has released hundreds of thousands of roach and bream larvae into the River Witham to help waterways recover from a major pollution incident.
Ammonia contamination in the Southrey area in March was responsible for the death of at least 100,000 fish and investigations into the incident are ongoing.
The EA has promised to bring those responsible to justice as well as ensure the local rivers recover as quickly as possible.
The release of larvae on Friday, May 25 is the first step in the important recovery process – but experts added it could take a number of months and up to several years for the river’s complex ecosystem to return to full health.
The fish larvae have come from the EA’s national fish farm in Calverton, which produces around 450,000 fish of nine species each year for restocking.
Calverton Fish Farm is funded by income from fishing licence fees, and last year it stocked out over six million advanced reared larvae back into the wild.
Environment Manager Simon Mitchell said: “According to our latest estimates, the pollution incident in March caused the death of no fewer than 100,000 fish – although the exact figure is likely to be higher.
“As a river is a complex ecosystem with different species recovering at different rates, the full recovery process may take numerous months up to several years.
“We take pollution incidents like this extremely seriously and will always seek to prosecute those who negligently damage our precious environment and wildlife.
“We have staff continuing to work on this pollution incident full-time, as the river progresses through the recovery phase.”