Climbing perch – which have lungs as well as gills – pose a hazard to birds, turtles or other fish that make the mistake of trying to eat them because they can swell up in the windpipes of their would-be predators and choke them to death.
The bizarre spiky fish are native to South-East Asia, but have spread south through Indonesia and Papua New Guinea over the past four decades, according to the Australian Broadcasting Corporation. They have now been found on two Queensland islands less than 100 miles from the northernmost tip of mainland Australia.
Nathan Waltham, a senior researcher at James Cook University, told the Guardian it would be a “major disaster” for native fish and other wetland species if the climbing perch did make it to the Australian mainland.
“Their gill covers – they can flex them out and get caught in the throats of fish and birds, so that leads to the animal dying,” he told ABC.
Climbing perch grow to about 10 inches in length and have lungs next to their gills. They are known to hibernate for up to six months in the mud of dried-up creek beds. Waltham doubts the fish will reach mainland Australia by swimming – or walking – but fears that they could arrive in the bottom of a fishing boat or as discarded live-bait.
Damien Burrows, of James Cook University, told ABC: “Anecdotes are that they are carried between villages o various islands. So a trip in a boat across the Torres Strait is not out of the question.”