If you’re fishing in the UK, you might expect to catch a trout or a tench, perhaps a carp if you’re lucky. So, you can only imagine the surprise of discovering a razor-toothed piranha, more typically found in the rivers of the Amazon Basin, than a lake in an English town.

At least two suspected piranhas have been found in the not-so-tropical Martinwells Lake in Edlington, in South Yorkshire, also known as Edlington Brick Pond. On both occasions, the ferocious little beasties were found dead and floating in the water by a passerby, the Doncaster Free Press reports.

As if that wasn’t suspicious enough, locals had previously noticed that the lake didn’t have as many ducklings as previous springtimes. Fish were also in seemingly short supply. Perhaps it’s a coincidence, or perhaps a blood-thirsty carnivorous predator was on the loose...

“People have been saying for a few weeks that they have been finding it difficult to catch fish in the lake and there’s normally loads of ducklings on there too but this year we’ve hardly seen any,” Toni Hooper, who discovered the second body, told Doncaster Free Press

“It makes you wonder if it is piranhas that have been going around killing them.”

Local authorities are warning people not to swim or fish in the lake, just in case any more carnivorous suspects are at large. So do piranhas deserve their fearsome reputation? Attacks on humans are rare, but a gang of piranhas is perfectly capable of causing some real damage to a human. Schools of piranhas attack their prey en masse, whether it be fish, birds, or mammals, by nipping at their flesh with their notoriously sharp teeth.

Being eaten by piranha is even rarer. According to one scientific study from 2003, there have been very few documented cases of humans being eaten by piranha, and at least three of them occurred after the person had died of other causes – as a result of drowning or heart failure – rather than death-by-piranha. Most attacks, however, only result in minor injuries, some painful nibbles, and on occasion, the loss of a finger. 

The question remains though, how did a pair of freshwater fish, native to the warm Amazon basin, end up over 8,000 kilometers (~5,000 miles) away in the north of England?

The UK Environment Agency is carrying out lab tests on the specimens to investigate the strange goings-on, but the most likely circumstance is that the piranhas were once pets, but were either unwanted or became too large for their tanks. Perhaps naively, their owner released them into the lake to be free and they promptly perished in the comparatively cold water temperatures of the UK.

“Given the natural habitat of piranhas, it is highly unlikely that the fish were alive at any time in the lake,” said Gill Gillies, assistant director of environment at Doncaster Council.

“We assume that these were pets that were placed in the lake, something that we would strongly discourage people from doing.”