A WARNING not to eat fish, crabs or shellfish has been extended from the Swan to include parts of the Canning River.
The Health Department confirmed testing had identified elevated levels of the same, potentially toxic alexandrium algae.
A health warning has been extended to take in waters from the South of Perth Yacht Club to Como Jetty and upstream to Kent Street Weir.
The update follows earlier health advice, warning people not to eat fish, crabs or shellfish collected from within the Swan River.
The warning zone extends from Pelican Point to Como Jetty and upstream to Tonkin Highway Bridge.
This area includes the commonly known areas of Matilda Bay, Perth Waters, Elizabeth Quay, Barrack Street Jetty, Claisebrook Cove, Maylands Yacht Club, Ascot Waters and Riverside Gardens.
“The ingestion of toxins produced by this microscopic species of algae can produce a type of poisoning known as paralytic shellfish poisoning (PSP),” the Health Department said in a statement.
“Cooking will not destroy these toxins.
“In severe cases PSP may cause muscular paralysis in people who consume affected shellfish, crabs or fish. Shellfish includes oysters, mussels, clams, pipis, scallops, cockles and razor clams.
“Anyone who has consumed shellfish, crabs or fish collected from the affected area of the Swan River and experiences symptoms should seek urgent medical attention, particularly if they have difficulty breathing.
“They should also retain uneaten portions of mussels or other shellfish to help determine a likely cause of any symptoms.”