Published: 12:05, 05 August 2019
| Updated: 14:14, 05 August 2019
People are being discouraged from entering a river after fish were found dead.
The authority believes the issue could be due to recent hot weather affecting oxygen levels in the water.
It is working with the Environment Agency and the Internal Drainage Board to determine what action to take.
"We would not encourage anyone to enter the water course or carry out clearance works without first approaching the council for approval as the area contains wildlife habitats that are protected by law and any person disturbing these habitats may be liable to prosecution."
Frank Todd was walking along the Rope Walk, close to Gulf petrol station, when he spotted the lifeless animals among the algae in the water, last Tuesday.
He posted the images on a local Facebook page sparking a debate among residents.
They commented on the overgrown weeds and lack of maintenance and raised concerns over other fish known to the waters, such as carp.
Others advised dog owners not to allow their pets near the water.
The Environment Agency has been approached for a comment.