A Maltese marine biologist is sounding the alarm as the venomous lionfish (Pterois miles and Pterois volitans) continues its relentless spread across the Mediterranean Sea, and it's edging ever closer to Maltese waters.

Professor Alan Deidun, one of Malta’s leading marine biologists, recently shared an updated lionfish distribution map from a 2025 study by Azzurro et al., expressing deep concern about the invasive species' rapid advance. ‘Spreading through the Mediterranean like hell and edging ever closer to Maltese waters,’ he wrote in a stark social media post, emphasising the growing ecological threat.

Native to the Indo-Pacific region, lionfish are easily recognised by their dramatic red and black bands, showy fins, and venomous spines. While beautiful, these predators are anything but benign. Known for their voracious appetite and lack of natural predators in foreign waters, lionfish consume a wide variety of fish, including species critical to local ecosystems. Their presence can decimate native populations, unbalancing entire marine habitats.

And they’re not just a threat to marine biodiversity – lionfish are also dangerous to humans. Their venomous spines can cause severe pain, paralysis, and in extreme cases, cardiac arrest or death, making them a serious risk for swimmers and divers too.

Malta first recorded a lionfish sighting in 2016, when Professor Deidun issued an early warning. In 2019, there was another sighting, and a reward was offered to anyone who could catch it. Despite the island’s initial low number of sightings, recent trends across the central and eastern Mediterranean suggest that Malta could soon face a full-blown invasion.

In an effort to fight back, Professor Deidun launched the ‘Spot the Alien Fish’ campaign, a citizen science initiative aimed at raising public awareness and encouraging residents to report sightings of invasive marine species. The platform (campaigns.ocean.mt) allows anyone – from recreational divers to fishermen – to log encounters and help experts track the lionfish’s advance.

Aside from reporting any sightings, you can also keep safe by staying alert while swimming, diving, or fishing, especially in deeper or less frequented waters.

Have you ever spotted one?