Are there Alien Fish in Maltese Waters?

The simple answer is ‘yes.’

Very recently, the aliensmalta http://www.alienmalta.eu science campaign was alerted to a fish species caught within the Maltese waters. This alien fish was identified as a silver-cheeked toad-fish, which is highly toxic if consumed.

Where does it originate from?

This alien species of puffer fish is actually native to the tropical waters of the Indo-Pacific and Indian ocean regions. In 2004, a sighting of the silver-cheeked toadfish was recorded in the Mediterranean, off the coast of Turkey. It lives in open waters on rocky bottoms, from in shallow depths down to 250 m.

Spot the Alien Fish campaign.

This is a citizen science campaign set up in Malta, funded by the International Ocean Institute (IOI) and the Department of Fisheries and Aquaculture (DFA-Malta). It allows Maltese citizens to submit photos and report alien fish that have been spotted in Maltese waters.

Silver-cheeked Toadfish (Lagocephalussceleratus)

This species of alien fish arrived into the Mediterranean via the Suez canal. It is classed as a marine bony fish in the family Tetraodontidae. It is extremely toxic if consumed and is responsible for a growing amount of mortalities. Sadly, in many fisher communities there is a lack of awareness about this species; this includes Egypt and Tunisia. It has been reported off Lampedusa Island, Crete and Cyprus.

Description.

The silver-cheeked toadfish is more elongated than the oceanic pufferfish. It has a symmetrical caudal fin (tail fin) with a characteristic silver band, which runs along its sides. Its back is brown or grey with darker spots. The belly is white.

Food.

The silver-cheeked toadfish preys upon benthic invertebrates. These organisms live at, in or on the seabed where the silver-cheeked toadfish feeds.

Toxins.

The silver-cheeked toadfish, which belongs to the puffer fish family contains a venom by the name of Tetrodotoxin (TTX). This venom is a non-protein neurotoxin and is extremely potent. This TTX toxin is found within the organs of this alien species. It is found in the kidneys, liver, muscle tissue and ovaries.

Invader of the Mediterranean Sea.

During the last few years, this alien species of fish has been caught at least three times in Maltese waters. The latest individual to be landed recently, was at the mouth of Gnejna Bay on Malta. It is classed as one of the worst marine invaders of the Mediterranean Sea. The silver-cheeked toad-fish comes to the Mediterranean Sea via the Suez Canal.  Onward, it continues its journey West, until it reaches Spanish waters.

What are the symptoms of TTX poisoning?

The victim will experience nausea and dizziness. A body tingling sensation will spread through the body, accompanied by abdominal pain and a headache. The victim is in grave danger of muscular paralysis of the limbs.  Cardiac arrest is likely if the case is unattended or stays unassisted. In Japan and Bangladesh, the average mortality rate of TTX poisoning is around 10%.

The production of TTX?

Marine bacteria is the actual producer of TTX, which may come as a surprise. The puffer fish family (Tetraodontidae) accumulates TTX within their body tissue. The toxin derives from the organisms they consume. The ability to take TTX on board will dissuade any predators who are in search of prey.

Where to report these sightings?

A campaign, run by the Department of Geosciences at the University of Malta. You can download the app and report any alien species, along with good quality photos at www.alienmalta.eu

A good way to learn more about fish species and families, is to come and do a PADI Fish Identification course with us at Dive Smart Gozo.