Fairfield mayor Frank Carbone is asking residents to report any sightings of the illegal water plants, frogbit and water lettuce - either in waterways or being sold for aquariums and household garden ponds.
It comes as Fairfield Council have seen the banned aquatic weeds for sale in the past few weeks.
“We want residents and families to be able to get outdoors and enjoy our natural waterways,” Mr Carbone said.
“To enjoy our creeks, we need to keep them free of the foreign invaders that destroy the creeks’ ecosystem. If you see these weeds in our creeks, please let council know immediately.
“Council will work closely with the NSW Department of Primary Industries to ensure a rapid response to any sightings."
Frogbit, which seriously damage the waterway ecosystem, has been banned from sale since 2014, but is still found in homes in fish ponds, aquariums and water features. Heavy fines can apply for the sale of these plants.