Melissa Walker, Industry & Investment (I&I) NSW Acting Manager Aquatic Biosecurity and Risk Management, said the fish, known as the Pearl Cichlid or Pearl Eartheater (Geophagus braziliensis), was first reported in the areas around Murwillumbah and Uki in late 2008.
The pest fish is believed to have been released into local waterways from a personal aquarium.
“This is another example of a new potential pest entering our waterways and threatening the local aquatic life through the careless actions of one or two people,” Ms Walker said.
“In recent months we’ve received new reports of the pest fish being spotted near Dum Dum on the Tweed River and again at Doon Doon Creek, below Clarie Hall Dam, on a tributary of the Tweed River.
“These new reports, together with the repeated floods experienced over the last year, have raised fears the cichlid may have become more widespread.
“Even if their numbers are low at the moment, there is a danger they could become much more common in the future.”
The department is concerned what impacts the pearl cichlid may have if it becomes more widespread and common in the river system.
“Unfortunately there is little I&I NSW can do to eliminate this pest, because they have been seen over such a large area, because they are so difficult to find and even harder to catch,” Ms Walker said.
“The best we can do is to get rid of them opportunistically when we come across them. The more people we have helping, the more chance we have of keeping a lid on their numbers.”
For this reason I&I NSW is appealing to anglers to keep a look out for the cichlid, and not return any they catch to the water.
“If you catch one while fishing, the best thing is to take a photo, freeze it and record exactly where you caught it, then call I&I NSW on 02 4916 3877 to let us know,” Ms Walker said.
The species, which is a native of South America, is a popular aquarium fish, having an attractive pattern of pearly spots over a grey-green body with red or red-edged fins.
When breeding, a pair cleans a nesting site and guards the eggs, and may be very aggressive to other fish which enter their territory.
It is an extremely hardy fish, being able to survive in water temperatures down to around 10°C, and in full-strength seawater.
“Aquarium fish only belong at home in a fish tank. If you have unwanted fish, take them back to a pet shop, give them to a friend or dispose of them in a humane way,” Ms Walker said.
“Never, ever dump pet fish into the wild.”