Thursday, 21 February 2008


Attack of the killer fish?

It sounds incredible.

Apparently a savage fish more terrifying than a piranha is invading the UK. It can even "kill people". Sorry, I mistyped that quote, it should be "KILL people".

The story that's got The Sun newspaper and a few other tabloids in a feeding frenzy is a report that a fish called a giant snakehead has been caught in the River Witham in Lincolnshire.

An angler caught the fish last week and sent a photo to a fishing magazine called the Angler's Mail, which forwarded it to the UK's Environment Agency. There, an agency spokesman told me, fisheries expert Nigel Hewlett tentatively identified it as a giant snakehead, Channa micropeltes, originally from east Asia.

Now, the giant snakehead is a voracious eater of other fish and has a set of very sharp teeth. It can also grow to over a metre long and weigh over 20 kilograms. But can it really kill you? At first I assumed too many people had watched Swarm of the Snakehead while taking non-approved pharmaceuticals.

The Environment Agency spokesman also dismissed the claims that it was a man-eater, suggesting the snakehead is no more dangerous than the UK's native pike. And at first I believed him.

After all, it's hard to believe The Sun's story when the photo they used is not of the fish caught in Lincolnshire nor even a giant snakehead. In fact, it is an archive shot of a northern snakehead, Channa argus, as is another photo used in a couple of other newspapers.

Yet to my amazement, there really are reports of deaths attributable to the giant snakehead, as outlined in this description of the species.

"It will attack people," the author of that description, zoologist Walter Courtenay of the US Geological Survey, in Gainesville, Florida, told me. "And there have been reports of deaths, of children being dragged under."

According to Courtenay, parents make nests in which they lay their eggs and raise their fry, and any animal perceived as a threat is attacked ferociously. He thinks the giant snakehead is more dangerous than the piranha.

Courtenay was sent photos of the fish caught in Lincolnshire by Ben Weir of the Angler's Mail, and he says it is definitely Channa micropeltes.

So should we be afraid? Er, no.

The giant snakehead is a tropical species and there is no way it could survive winters in the UK, says Courtenay. The fish found in Lincolnshire was probably released recently after it outgrew someone's aquarium, and it died soon after being caught.

So there you have it. Personally, I'm still not entirely sure I believe these reports of people being killed. Fishermen are notorious for their tall tales. Courtenay has given me details of a local expert in Thailand who apparently knows details of attacks, so I'm going to wait to hear what he tells me before making up my mind.

After all, both scientists and the media seem eager to demonise snakeheads, as happened when northern snakeheads were discovered in the US in 2002, with one state biologist describing it as "the baddest bunny in the bush". Sure, the northern snakehead is a problematic invasive species that can alter ecosystems, but claims that it wipes out all other fish are just not true.

Update: Those of a sensitive disposition look away now. Ben Weir of the Angler's Mail has kindly sent us the picture, taken on a mobile phone, of the terrifying "killer fish" caught by angler Andy Alder.

Michael Le Page, biology features editor, New Scientist
(what does he mean, fishermen are renowned for tall tales?)