Inland Fisheries Ireland (IFI) said over 1,000 dead carp have now been removed from The Lough, on the southside of the city, and from the privately owned Belvelly Lake near Cobh since concerns about fish health were raised just over two weeks ago.
Experts at the Marine Institute are still running tests on samples taken from both locations. Results are expected next week.
IFI said, in the meantime, the suspension of angling at Inniscarra and Carrigadrohid will continue until May 31 as a precaution.
The Fish Health Unit of the Marine Institute has been testing carp taken from The Lough and Belvelly to determine the cause of the fish deaths.
All tested positive for carp edema virus (CEV) but further tests, which will include sequencing of the viral DNA to confirm its identity, are continuing.
Luckily, tests for the koi herpesvirus disease, a listed disease under European Fish Health legislation, were negative.
The institute’s director of marine environment and food safety, Dr Jeff Fisher, said while they can’t determine yet how the “disease agent” was introduced, the scale of carp deaths highlights the need for anglers and other recreational users of Irish waters to clean their equipment, to be aware of the potential risk of transferring fish that may carry disease into the wild, and to never release ornamental fish into lakes or rivers.
He said the relevant bodies are continuing to try to determine the cause of the fish kill, contain the incident, and identify appropriate biosecurity measures for the future.