A species of puffer fish, identified as the silver-cheeked toadfish, is rapidly expanding its territory throughout the Mediterranean Sea, posing a risk to swimmers and fishermen due to its toxic flesh and formidable jaws. Local authorities in Greece have begun implementing protective measures, including the installation of floating barriers, to safeguard the public.
The silver-cheeked toadfish, also known as harefish, entered the Mediterranean via the Suez Canal and its presence has been linked to warming sea temperatures. The fish contains tetrodotoxin, a potent neurotoxin concentrated in its flesh and internal organs, making it dangerous to consume. Its beak-like jaws are capable of shredding fishing gear and have been known to bite through bone.
Authorities have issued warnings to tourists and locals regarding the potential dangers. A study published in the journal Toxics documented 198 human health incidents related to invasive puffer fish in the eastern Mediterranean between 2004 and 2023. These incidents included 28 physical attacks, 144 non-lethal poisonings, and 27 fatalities. Researchers noted a significant increase in recorded incidents after 2019, though the cause—whether increased media attention or greater fish abundance—remains unclear.
The Hellenic Red Cross cautioned that no part of the fish is safe to eat due to the varying distribution of tetrodotoxin. While the fish's bite is not venomous, its powerful jaws can inflict serious injuries and significant bleeding. The toxin can cause paralysis and respiratory failure, with severe poisoning potentially leading to cardiac effects.
In response to the growing threat, Greek authorities have installed floating barriers in the Gulf of Euboea, separating the mainland from the island of Evia, to create safer swimming areas. Other municipalities along the gulf are also deploying or planning to deploy similar protective nets. While the fish have not been sighted in major Greek island resort bathing areas, they have caused problems for fishermen near Crete and other islands, damaging nets.
The silver-cheeked toadfish faces few natural predators in the Mediterranean, contributing to its population growth. The Greek government has initiated a program to pay fishermen 5.33 euros per kilogram (approximately $2.75 per pound) to catch the invasive species.