Zombie fish start stalking Melbourne's aquarium, decades after apocalypse

Conservationists have begun a breeding program for central Victoria's southern purple-spotted gudgeon, a species dubbed the zombie fish two decades after their apparent extinction.

It is part of a wider resurgence of fish whose apocalypse is thought to have been triggered by habitat destruction, feral species and river regulation.

Experts could soon decide whether to release the fish into newly restored frog ponds at an old industrial site in East Bendigo, North Central Catchment Management Authority project officer Peter Rose said.

"We are getting closer to a decision on that one, pending permits and approvals," he said.

"We've done some surveys to make sure there are no alien fish species there. We've had a look at the habitat and water quality and everything's looking pretty good."

The east Bendigo site would be the fourth site in the region that southern purple-spotted gudgeons have been introduced thanks to Victorian breeding farms.

There are others in Mildura and Deniliquin.

The idea has been to put the fish on farms and in closed off water bodies where they can be monitored.

Conservationists have returned a few months later to find fish twice as big.

"They've actually bred at three of the sites already," Dr Rose said.

New Bendigo fish would likely come from existing farms for now, rather than Melbourne's aquarium, Dr Rose said.

But the facility could give sub-juveniles the perfect habitat conditions.

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Those fish could start reproducing within six months, the aquarium's curatorial supervisor Sam Fawke said.

"Once they are around 2-3cm long, the next step will be to rehome the new generation into pest-free 'surrogate' sites to further establish the population before hopefully reintroducing them in native wetlands around northern Victoria," he said.

The first two southern purple-spotted gudgeons were rediscovered near Kerang in 2019.

Conservationists soon realised a small colony had held out in the area.

The fish grow up to 12cm and prefer to live in dense reeds. They vary from purplish-brown to yellowish-brown, with a rounded head and a small mouth.