Fish are being removed from the River Teme in Herefordshire over fears for their health as water levels fall.
The Environment Agency has spent Thursday stunning the fish and then taking them elsewhere in the river where there is deeper water.
A spokesman said there has been a seven month period of below average rainfall which has left fish stranded in isolated pools.
They are at risk of suffocating due to lack of oxygen, he said.
Fisheries specialist Chris Bainger said the fish were stunned using a light electric current.
"We are concerned the continuing dry weather may affect more wildlife, including fish and plant life in and around rivers and lakes," he said.
The agency will continue to monitor the situation.