Aggressive as pitbulls, prolific breeders and packed with a heart-stopping toxin, they are a fisherman’s worst nightmare.
Growing to a length of three feet or more and weighing in at a chunky 20lbs, silver-cheeked toadfish use their sharp teeth to tear into fishermen’s nets to get at the catch inside.
“They eat cuttlefish and octopus and calamari straight out of the net, before you can land it on the boat,” said Loucas Georgiou, standing on the quayside of the harbour in Ayia Napa in eastern Cyprus. “Fish like this are a catastrophe for the sea.”
Located at the eastern end of the Mediterranean, Cyprus is on the frontline of a marine invasion – in recent years more than 800 species have arrived via the Suez Canal from the tropical waters of the Indian Ocean.
They include parrot fish, the Red Sea goat fish, the dusky spinefoot, trumpet fish and new species of sea urchins.
Within Cyprus, the hotspot for new arrivals is Cape Greco in the far south-east of the island, a rocky headland where crystal clear bays give way to the deep indigo blue of the open sea.
What was once a trickle has become a flood, aided by the widening of the Suez Canal, which has changed salinity levels that previously acted as a barrier to migration.
The toadfish – also referred to in Cyprus as the puffer fish – is a particular challenge.
Not only does it prey on native species, it is also highly venomous.
Because the flesh of the fish contains toxins, it cannot be eaten. So fishermen who inadvertently catch the species are paid a bounty of three euros a kilo to bring it to port.
The toad fish are then incinerated once a month in special furnaces, with around 50 tonnes burned each year.
“They’re very aggressive, they destroy the nets, they eat the catch inside. They are very adaptive. The species established itself really fast. They can eat anything,” said Nikolas Michailidis, from the department of fisheries.
“The fish contain a paralysing toxin – if you eat some, you stop breathing. A few milligrams can kill you. We asked the Japanese if they would be interested in importing our puffer fish but even they considered them too toxic.
“If you go snorkeling, most of the creatures you see were not here 10 years ago. I’m 43 years old and I’ve been fishing and snorkeling since I was small. Thirty years ago it was completely different.”
Alien fish from the Indian Ocean and Red Sea are being drawn into the Mediterranean by warmer waters, caused by global climate change.
The Mediterranean is in fact turning into a tropical sea due to rising water temperature, the World Wide Fund for Nature warned in a report released in June.
With temperatures rising 20% faster than the global average, the Mediterranean is becoming the fastest-warming sea on the planet, the Italian branch of WWF said.
“Urgent action is needed to further mitigate greenhouse gas emissions and adapt to the new reality of a warming sea,” the conservation organisation warned.
Demetris Kletou, a marine biologist, describes Cyprus as the “doorstep” of the Mediterranean – the first European country that these species reach after they swim past the coasts of Egypt, Israel and Syria.
From Cyprus, they are slowly moving west towards Greece, Malta, Italy and beyond on, with some already having reached the Straits of Gibraltar.
“Cyprus is the canary in the coalmine in terms of these new invaders. If we can keep track of the newcomers, if we detect them here, then other countries will have time to prepare for their arrival and adopt mitigating measures,” said Mr Kletou, from the Marine and Environmental Research Lab, a consultancy.
“With the sea warming as it is, Italy will probably be in the same situation as us in 10 or 20 years, for instance.”
In contrast to the silver-cheeked toadfish, another new arrival in Cypriot waters is eminently eatable – in fact it is delicious.
The catch is that the lionfish, one of the most spectacular looking species in the ocean, is festooned with poisonous quills.
Large noticeboards have been set up in Cypriot fishing harbours warning of the creature’s armaments – 13 venomous dorsal fins, three venomous anal spines and two equally dangerous pelvic spines.
“We’ve started seeing a lot of lionfish over the last two years,” said Julio Halal, a dive instructor who takes tourists diving off Cape Greco.
“Water temperatures are changing and that produces a new environment which can accommodate these tropical species,” said Mr Halal, who moved to Cyprus from Lebanon.
The good news is that fishermen in Cyprus have learned how to handle the fish, wearing heavy puncture-resistant gloves when they cut the quills off, and are beginning to sell them to restaurants around the island.
Teams of volunteer divers are sent out periodically to spear lionfish and from time to time there are lionfish “derbies”, open to all comers, contests to see how many can be caught.
The fish are then donated to restaurants, which are slowly managing to convince customers of the merits of lionfish.
It is all part of an EU-funded project called ReLionMed-Life which aims to monitor and control the population of lionfish in Cyprus waters.
“Maintaining the pressure on lionfish is important in keeping the numbers under control and as a bonus it’s very tasty,” said Periklis Kleitou, a marine scientist from Plymouth University who works on the project.
“Because Cyprus’ waters have been overfished, 70% of seafood is imported, so lionfish can be a solution in offsetting that. We just have to change the perception of the species and tell people that once you remove the spines, it’s delicious. Until a couple of years ago, fishermen would discard them. It is only recently that they are being eaten.”
Lionfish are to some extent compensating for the fact that fishermen are catching far fewer native species in the island’s waters.
But the overall impact of the arrival of exotic species has been huge.
“Some fishermen are saying their income has been cut by 50% because of the damage done to their nets by puffer fish and the loss of their catch,” said Mr Kleitou.
“Populations of lion fish are doubling every year and they’ve not reached a plateau yet.”
“At depths of 200m to 300m, the sea is full of puffer fish,” said Mr Georgiou, who found the alien invasion so dispiriting that he retired from fishing after 40 years at sea.
“It was my life. My father was a fisherman and so were my six brothers. Now, none of them are. If you can’t even cover your expenses, there’s no point.”
Fishermen are having to adapt swiftly to a wide array of new species turning up in their nets – some edible, others not.
“Some fishermen are now reporting that their catches consist of mostly alien fish, or even exclusively alien fish,” said Mr Michailidis from the fisheries department.
“You will never be able to eradicate these new species, it’s impossible. But you can have management plans.
“Even if we removed all the puffer fish from Cyprus waters today, in a month they will arrive from other areas. Most of these species are here to stay.”