A British tourist was taken to a private clinic after being bitten while swimming at Kalamaki on the Greek island of Zante. She told medics she had been bitten by a monkfish, but authorities are investigating and suspect the wound may have been caused by the invasive silver-cheeked toadfish, a toxic pufferfish spreading through the Mediterranean.

The fish’s powerful, beak-like teeth can cause serious injuries, and its flesh and organs contain tetrodotoxin, which can be fatal if eaten. Fishermen say it is damaging catches and nets, while reports of encounters with people have increased; a 2.5-kilometre floating barrier has been installed in bays off Evia. Researchers attribute its spread partly to warmer, more saline seas, and believe it entered the Mediterranean through the Suez Canal.