A species of puffer fish with toxic flesh and powerful jaws is expanding its range throughout the Mediterranean, prompting local authorities to issue warnings to tourists about the risk of bites. The invasive silver-cheeked toadfish, also known as the harefish, has entered the Mediterranean through the Suez Canal and has spread as sea temperatures have warmed. This fish carries a deadly neurotoxin called tetrodotoxin, primarily found in its flesh and internal organs. Its powerful beak-like jaws can also shred fishing gear and bite through bone, posing a significant threat to humans.
The fish's toxic flesh and powerful jaws have led to numerous incidents involving humans. Between 2004 and 2023, there were 198 reported human-health incidents involving invasive puffer fish across the eastern Mediterranean. These incidents included 28 records of physical attacks, at least 144 non-lethal poisoning episodes, and 27 human fatalities resulting from consumption of the fish. The number of recorded incidents has increased significantly after 2019, particularly with regard to poisonings, although the reason for this increase is unclear.
Local authorities have taken precautions to protect swimmers and bathers from the invasive fish. The Hellenic Red Cross has issued a public advisory cautioning that the fish's flesh contains a potent neurotoxin, making it extremely dangerous to eat. The advisory also warns that no part of the fish is considered safe to eat due to the varying distribution of the toxin. Additionally, the fish's powerful jaws can cause serious injuries and heavy bleeding, even though its bite is not venomous.
Tetrodotoxin, the neurotoxin found in the fish, can cause paralysis and respiratory failure, as well as cardiac effects in severe cases. To mitigate the risks associated with the fish, Greek authorities have established floating barriers beneath the Gulf of Euboea to safeguard people in the water. Other municipalities along the Gulf of Euboea are also installing or planning to install floating barriers and protective nets to help keep swimmers safe.
The silver-cheeked toadfish has few natural predators in the Mediterranean, allowing its population to grow rapidly. In an effort to control the population, authorities are offering to pay fishermen to catch the nuisance fish. While not all pufferfish are poisonous, the vast majority contain a lethal neurotoxin called tetrodotoxin in their internal organs and skin. The toxicity levels of this neurotoxin can vary significantly by species, and farm-raised pufferfish that never eat toxin-containing prey in the wild remain non-toxic.
Despite the risks associated with the silver-cheeked toadfish, authorities say the fish have not been sighted in bathing areas at Greek island resorts. However, the fish have caused problems for fishermen off the coast of Crete and several other Greek islands, damaging their nets and equipment. To address this issue, authorities are taking a proactive approach to protect both humans and the fishing industry from the invasive species.
