Sydney, June 2 (IANS): Scientists alerted Australian authorities of the risks faced by the fauna with the advance of a species of fish from Papua New Guinea, academic sources said on Tuesday.

The climbing perch (Anabas testudineus), a fish that can live up to six days out of water and crawl across dry land, has already infested two remote islands in northern Australia -- Boigu and Saibai -- located in Torres Strait, six km south of Papua New Guinea, Efe news agency reported.

Nathan Waltham, a scientist from James Cook University heading the team monitoring the spread of this fish in the Torres Strait, believes that it will be difficult to eradicate it from Boigu and Saibai where its presence was registered in late 2005.

The climbing perch also appears to have developed the ability to tolerate salt water.

"In our trip up there in December we found it in some hyper saline water holes, so there is some ability to resist exposure," said Waltham.

This fish, which is believed to have reached Australian islands after an overflow of water from the rivers near Papua New Guinea, is listed as a highly invasive species that competes with native species once it settles into a new habitat.

The climbing perch can also hibernate on dry river beds up to six months.

If eaten by other larger animals, the perch is capable of choking their throats by stretching its dorsal fins thereby causing the predator to die.

Scientists believe that their new ability to resist salt water perhaps can help them move closer to Cape York, from where they can invade the Australian mainland, a new possibility that is being studied as a precautionary measure.

"I still think the chances of it getting to Australia by swimming are quite low," said Waltham.

"There is more chance it will arrive in the bottom of a fishing boat or as discarded live-bait fish," he added.

Australia has a very fragile ecosystem that has been disturbed by pests like the American toad, foxes or rabbits causing serious environmental problems.