Toxic fish caught once again in Maltese waters

The Spot the Alien Fish citizen science campaign (www.aliensmalta.eu) has recently been alerted to the capture of yet another individual of the toxic silver-cheeked toadfish (Lagocephal ussceleratus), an alien species of puffer fish native to tropical Indo-Pacific regions which was first recorded in the Mediterranean in 2004, off the coast of Turkey.

According to campaign coordinator Alan Deidun, the species is extremely toxic, such that it’s consumption is responsible for a number of mortalities in countries characterised by a lack of sufficient awareness among fishing communities, including Tunisia and Egypt. The toxic nature of the fish is due to the presence of the TTX (tetrodotoxin) venom – one of the most potent non-protein neurotoxins known to man – which infuses different organs within the fish, including the kidneys, liver and ovaries, besides muscle tissue.

As a result, this fish species, which has been caught on at least three different occasions within Maltese waters, is considered to be one of the worst Mediterranean marine invaders, having spread all the way from the Suez Canal to Spain. Symptoms of TTX poisoning include a tingling sensation over the entire body, nausea and vomiting, dizziness, headache, abdominal pain and muscular paralysis of the limbs, with cardiac arrest resulting in extreme and unassisted cases. Intriguingly enough, TTX is produced by marine bacteria and members of the puffer fish family (Tetraodontidae) have the capacity to accumulate TTX in their tissue as a way of dissuading predation. On average, a mortality rate of 10 per cent is reported for countries where cases of TTX poisoning are reported, including Japan and Bangladesh.

The latest individual for this species was caught by a veteran fisherman off the mouth of Ġnejna Bay, at the same spot where the first individual of this species was caught in 2015. The Spot the Alien Fish campaign is run by the Department of Geosciences at the University of Malta and is supported by the International Ocean Institute (IOI), the Environment and Resources Authority (ERA), the Department of Fisheries and Aquaculture and the Malta Tourism Authority (MTA).

Those interested in supporting the initiative by submitting their reports of marine alien species (not just fish) are encouraged to download the campaign smart phone app, to join the campaign’s social media page, and to visit the campaign’s website, from where complimentary copies of the user-friendly, flagship campaign A3 poster can be requested. Reports should be accompanied by good-quality photos and, where possible, the fish individual should be adequately preserved (e.g. through freezing) when caught.