A poisonous feral fish species has been completely eradicated in the Top End thanks to a year-long Indigenous collaborative project that has been hailed as a biosecurity success story.

Larrakia Traditional Owners have stamped out a toxic aquatic pest from One Mile Dam, a sacred site in a tiny Aboriginal community on the edge of Darwin's CBD.

Gambusia holbrooki, also known as mosquito fish or plague minnow, was discovered in a drain near the community in 2014.

Gambusia was introduced to Australia as a biological mosquito control, but it had little impact. It grew rapidly and competed with many native fish and frogs.

The North American gambusia holbrooki grows to a length of 6cm, but has a voracious appetite. It also threatened to devastate Tasmania's native fish and frogs.

Source: AAP Image/Threatened Species Network/Stephen L. Dogget

Senior Larrakia Traditional Owner Eric Fejo said once they had become aware of the noxious fish in the water, they were keen to remove it before it spread.

"We received support from neighbouring Aboriginal groups to help us get rid of the nasty critter," he says.

"Traditional Owners from as far as Kakadu were also worried about that fish getting into their pristine waters - that's our 'bush telegraph' working for us."

Prior to starting the project, native fish and freshwater turtles were removed from the dam and transported to Darwin Aquaculture Centre for safekeeping.

They were later returned to the dam to help rebuild their populations.

Traditional Owners used their knowledge to eradicate the gambusia. They utilised a tree root-derived poison called rotenone, used by ancestors to harvest freshwater fish.

"The organic compound rapidly biodegrades, so harmful residues were minimal and only small quantities were required," Robert Carne, Senior Indigenous Policy Manager at the Department of Primary Industry and Resources says.

The project was dedicated to the memory of the late Mr Timber, a much-loved community leader whose full name is not being used for cultural reasons, and who died suddenly in March.