Also courtesy of the ABC

The Northern Territory Fisheries Department fears a foreign species of fish is heading to the Territory and says it should strike fear into fisherman.

The tilapia fish reproduces in huge numbers and eats the food sources of native fish like barramundi.

Fisheries' aquatic pest management coordinator Helen Cribb compares the fish to another well known pest marching across north Australia - the cane toad.

"They'll basically take over a habitat. They're a stronger competitor, reproduce in larger numbers, able to tolerate a broader variety of conditions with a much wider food source.

"They're effective competitors and they're also a very aggressive species, so they will push other species out of the way."

She says the aggressive fish has recently been spotted in Queensland's river systems which drain into the Gulf of Carpentaria, and are now posing a major threat to the Top End's freshwater ecosystems.

The tilapia fish is about 30 centimetres long, either dark grey or dark olive green in colour and has a pointed dorsal fin.

Anyone who spots the fish is urged to contact the department.