Keepers opened the frog's normally isolated bunker to show off their prodigy for the cameras and to discuss their hopes that this group might hold the key to bringing the species back from the brink of extinction

The frogs hatched from eggs collected from Mount Baw Baw in 2013, and the zoo's amphibian specialist, Deon Gilbert, said creating a genetically diverse group to breed from is a priority.

Breeding is not possible until they reach sexual maturity at about six years of age, while they can live up to 30 years, Gilbert said.

"The frogs reach a maximum of six centimetres at maturity and live underground, which has made them a difficult subject for experts to observe in the wild," he said.

"Not a great deal is known about them, but they are a good indication of environmental fitness in their natural habitat."

A recent field trip discovered their numbers in the wild have shrunk 30 per cent in the past two years. The Amphibian Chytrid Fungus, which originated in Africa, is the main cause of the frog's decline. Gilbert said the fungus attacks their skin and tadpole development.