After the species was almost wiped out in the Millennium Drought, hopes are high for an attempt to restore the Yarra pygmy perch along the River Murray.
About 7000 of the tiny native freshwater fish - the Nannoperca obscura - have been released at three sites near Hindmarsh Island in an attempt to re-establish the species in the wild.
Yarra pygmy perch were first detected at Hindmarsh Island in 2002 but have been known to inhabit areas of south-eastern Australia since the late 19th century.
A group of aquatic ecologists, initially led by Michael Hammer, banded together to work out a way to secure the future for the species, saving the last remaining fish from the river to breed in surrogate breeding dams on private properties around the Adelaide Hills, Barossa and Fleurieu regions.
While there have been two previous - unsuccessful - attempts to save the extinction-threatened species, Nature Glenelg Trust senior aquatic ecologist Sylvia Zukowski is optimistic.
"We have a much better understanding of the habitat, vegetation and flow conditions that Yarra pygmy perch favour and thanks to the generosity of private landholders who provide their dams as surrogate refuge breeding sanctuaries, we have high numbers of beautiful healthy fish to release," she said.
"So, we're more confident that these latest releases will survive long enough to breed the next generation.
"This is great news, and hopefully will be the start of the end of the extinction of the Yarra pygmy perch in the region.
"We will continue to monitor the species in the wild which will provide important information for future research, conservation and management directions."
Preferring still or slow moving waters, the species thrives in areas with aquatic vegetation which provides protection, food and breeding habitat.
The process included the use of soft release structures, which submerged in the river to allow the fish to acclimatise for two weeks before being released into the river.
In a positive sign, recent monitoring saw an encouraging number of Yarra pygmy perch recaptured before being rereleased.
Climate, Environment and Water Minister Susan Close said she was hopeful this effort would be successful.
"It is vital for the health of the River Murray and the Coorong that we have a diverse range of species," she said.
"These dedicated ecologists have worked for 15 years to bring this species back from the brink and I'm looking forward to seeing the results."
The project is a partnership between Nature Glenelg Trust, the Murraylands and Riverland and Hills and Fleurieu landscape boards, the University of Adelaide, Flinders University and the Ngarrindjeri Aboriginal Corporation.
