Deadly walking fish are slowly closing in on Australia

An aggressive walking fish headed for Australia yesterday. Picture: Xufanc/Wikimedia Commons

An aggressive fish that can walk has made it from Papua New Guinea to islands in the Torres Strait and now has mainland Australia in its sights.

The climbing perch is supposed to be a freshwater species, but scientists from Queensland’s James Cook University yesterday confirmed that they had found the fish surviving in salty waterholes on Boigu and Saibai Islands, more than four kilometres from the PNG mainland.

It can live out of water for six days, but the fact it was surviving in water with “twice the level of salt we have in the ocean” has ecologists worried. And it can walk.

“It’s hard gill plates can actually bend them forward, and with some sharp spines, if you can imagine, it will actually drag itself along the ground,” Dr Nathan Waltham told ABC Radio.

“So slowly walking from one waterhole across land, and eventually finding another waterhole.”

The perch is a deadly invasive species, especially for any native predators which don’t know what they’re swallowing.

Dead barramundi and catfish have been found on the islands with the perch stuck in their throats due to its strong gill cover. It can be equally fatal for birds and snakes.

In the last 40 years, it has spread to PNG from its native home in south-east Asia, and through Indonesia and Java, but Dr Waltham isn’t overly concerned about it making the trip to Australia.

At least, not by swimming.

“They would only come to Australia if people either carried them either in their boats or in their buckets, or some other mechanism,” he said.

Here’s a look at one in action.

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