Invasive "Walking" Fish That Suffocates Its Predators May Be Coming For Australia

James Cook University/Nathan Waltham

The climbing perch is every conservationist’s nightmare. The invasive species can crawl on land and live without water for an astonishing six days. The fish, known for its ability to suffocate its predators, may now be heading to Australia after spending the last four decades spreading through Indonesia and Papua New Guinea, with devastating consequences.

The climbing perch (Anabas testudineus) originates from south-east Asia and has been seen on the Torres Strait islands of Boigu and Saibai—Australia’s most northerly outposts. The fish is ‘extremely hardy’ and has successfully outcompeted native species when populating a new environment. Researchers say it will now be immensely challenging to remove the fish from the islands.

The climbing perch has been observed hibernating for up to six months in the mud of dried-up creek beds. Researcher Dr. Nathan Waltham told The Guardian the fish has “lungs” similar to humans, which allow it to “breathe air on land.” The climbing perch is even able to get itself out of the trickiest of situations by swelling up when swallowed by large predators, such as birds and other fish. As a result, the predator's throat is blocked and the animal ends up choking or starving to death.

While the climbing perch is unlikely to get to Australia by swimming, Waltham fears it could “arrive in the bottom of a fishing boat or as discarded live-bait fish.”

“We are now actively monitoring Climbing Perch in our wetlands and educating local fisherman to report sightings. It is important we don’t let them travel beyond our Island,” he said in a statement.

There is, however, some evidence that suggests the freshwater fish is able to tolerate saltwater. “It does seem to be able to handle a little bit of salt. In our trip up there in December we found it in some hyper saline water holes, so there is some ability to resist exposure,” Waltham adds.

Researchers are now investigating the climbing perch’s tolerance to saltwater and specific temperatures in the lab. They’re also studying just how fast the climbing perch is able to move across different types of terrain. 

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