Salmon and trout have been returning in large numbers to the river which passes through Boscastle, the Cornish village devastated by floods in 2004.
An estimated 440 million gallons of flood water poured through the historic village, washing vehicles into the harbour and beyond.
Floodwater swept away most of the fish in the River Valency, seeing numbers drop to a 20-year low.
Now the Environment Agency says the fish have come back.
Fisheries officer Rob Hurrell, said: "We're very pleased.
"It means the number of young salmon and trout have increased.
"It's also good for residents because they have healthy water quality."