Thousands of fish have been released into the River Trent following pollution incidents, including a stretch affected by cyanide.
A 30-mile (48 km) stretch between Stoke-on-Trent and Yoxall was found to contain cyanide and partially-treated sewage in October.
A survey along a 700m section found almost no evidence of living fish.
Seventeen thousand chub, dace, barbel and roach from the Environment Agency near Nottingham are being restocked.
They were taken from the agency's Calverton Fish Farm to four locations on Friday.
A total of 3,000 fish will be released at Walton Bridge, 5,500 at Weston, 5,000 at Shugborough and 3,500 at Wolseley Bridge.
Further restocking of the Trent and Tame rivers will reach 85,000 before Christmas.
In mid-October, Environment Agency officers were able to offset some of the damage by pumping oxygen into the water.
The public, farmers, anglers and boaters were warned to stay away from the water as a precaution and keep animals away.