The Malta Independent 28 May 2023, Sunday
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New fish species for the Mediterranean recorded in Malta

Thursday, 22 September 2022, 12:49 Last update: about 9 months ago

The Spot the Alien Fish campaign, one of the three citizen science campaigns coordinated by the Oceanography Malta Research Group within the Department of Geosciences at the Faculty of Science, has recently marked yet another landmark through the discovery of a new fish record for the Mediterranean.

Prior to it being caught in Maltese waters, the white unicorn Naso annulatus (Quoy & Gaimard, 1825) was, in fact, previously never recorded from the entire Mediterranean Sea, being native to the western Indian Ocean (e.g. eastern African coasts) and the western Pacific Ocean (e.g. coasts of Japan, all the way to the Hawaiian archipelago).


The species belongs to the Acanthuridae family, which includes surgeonfish, tangs and unicorn fishes and is popular as an ornamental species within aquaria. This first record of the white unicorn is considered a casual finding, given that it is too early to conclude whether the species has actually established itself within the Mediterranean. Given the sheer distance between the Suez Canal and the Maltese Islands, its passive spread to Maltese waters is also hard to hypothesize, leading researchers to conclude that its showing up in Maltese waters could either be due to a deliberate aquarium release or, less likely, due to a shipping-mediated introduction. 

The finding of the white unicorn was documented in a scientific paper recently published within the Biological Invasions Records (BIR) journal, Prof. Alan Deidun, is the coordinator of the Spot the Alien Fish campaign, as well as the co-author. The same paper documents the finding of the spotted scat Scatophagus argus (Linnaeus, 1766) and of the ridged swimming crab Charybdis (Charybdis) natator (Herbst, 1794) from Egyptian Mediterranean waters. The spotted scat is already known from Maltese waters. 

The Spot the Alien Fish is supported financially by the International Ocean Institute (IOI) and is a joint collaboration with the Oceanography Malta Research group within the Department of Geosciences at the Faculty of Science. The citizen science campaign has been documenting numerous first records of non-indigenous fish species for Maltese waters as well as occasional new records for the entire Mediterranean since 2016. Reports to the citizen science campaign can be made through the campaign’s website or social media page. Prof. Deidun is assisted by Dr. Adam Gauci and by Mr. Johann Galdies in the running of the same citizen science campaign. 

The publication documenting this latest find can be downloaded directly through the journal’s website.


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