Don’t be fooled by their good looks. When the venomous lionfish find themselves in a new ecosystem, they come, they see, they conquer. They did it to the Caribbean and the Western Atlantic, and now they’re doing it to the Mediterranean.

Researchers gathered reports of common lionfish (Pterois miles) sightings from fishermen and divers over the course of one year. Their findings showed that lionfish have colonized and established themselves across most of Cyprus' south-eastern coast and their numbers are set to rise.

According to a study in Marine Biodiversity Records, there were 23 new confirmed sightings of 19 individuals across the south-eastern side of Cyprus, including sightings in Larnaca, Zinovia wreck, and Protaras. Many of these sightings were of pairs of lionfish, suggesting to the researchers that they were breeding couples.

Lionfish is an umbrella term for the genus of Pterois that encompasses 12 recognized species. They’re well-known for their stunning coloration, which acts as a form of “aposematism” – an adaptation that advertises their deadliness through bright coloring to deter predators. They’re equally infamous for their venomous spines, which can cause humans intense pain, paralysis, cardiac arrest, and even death.

The species of lionfish are native to the Indian and Pacific oceans. They have previously built a reputation after “invading” and making themselves at home in the tropical waters of the Caribbean.

However, since the 1990s, there’s been mounting reports of these spiky beauties in Cyprus and the Med. This has come somewhat as a surprise to the researchers:

“Until now, few sightings of the alien lionfish Pterois miles have been reported in the Mediterranean sea and it was questionable whether the species could invade this region like it has in the western Atlantic,” Demetris Kletou, of the Marine & Environmental Research Lab in Cyprus said in a statement.

“But we’ve found that lionfish have recently increased in abundance, and within a year have colonized almost the entire south-eastern coast of Cyprus, assisted by sea surface warming.”

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But what has caused this sudden deluge of lionfish to the Mediterranean Sea?

Egypt is undergoing a huge expansion of the Suez Canal, the artificial waterway in Egypt that links the Mediterranean Sea to the Red Sea. The researchers believe this could have allowed lionfish larvae to get through to the Mediterranean. Additionally, the warming waters from climate change has meant the Mediterranean water has become similar to that of their native seas.

Co-author Professor Jason Hall-Spencer, of the School of Marine Science and Engineering at Plymouth University, explained: "Groups of lionfish exhibiting mating behavior have been noted for the first time in the Mediterranean. By publishing this information, we can help stakeholders plan mitigating action, such as offering incentives for divers and fishermen to run lionfish removal programs, which have worked well at shallow depths in the Caribbean, and restoring populations of potential predators, such as the dusky grouper.

“Given that the Suez Canal has recently been widened and deepened, measures will need to be put in place to help prevent further invasion."