Loughs Agency has urged anglers and the public not to remove fish from the river.
The Loughs Agency, in conjunction with the NI Environment Agency, are currently investigating the cause of the fish kill. A spokesperson said: “Loughs Agency and NIEA staff have been gathering fish to be used as evidence in the investigation.”
Anyone with information relating to the fish kill or location of dead fish, is asked to phone 028 7134 2100.
The Loughs Agency also praised Faughan Anglers for their “ongoing support”.
Foyle People Before Profit MLA Eamonn McCann has warned that from being one of the best salmon rivers in Europe, the Faughan is now in crisis, while Sinn Féin Councillor Paul Fleming said that anyone found in breach of environmental regulations must be investigated and prosecuted.