Portent or accident? Two new records of thermophilic fish from the central Mediterranean

Abstract

The blue tang Acanthurus coeruleus Bloch and Schneider, 1801 and the Red Sea bannerfish Heniochus intermedius Steindachner, 1893 are reported for the first time from the Maltese Islands, which also represents the first central Mediterranean record for both species. The new records are based on an individual of A. coeruleus observed in October 2013 and a specimen of H. intermedius caught in November 2014; no individuals of either species have been found since. The occurrence of these species in Malta may be due to a westwards range expansion in the Mediterranean, given that both species were previously recorded from the Levantine Sea, but they could also have been introduced directly in Maltese waters through the aquarium trade or by shipping, particularly since evidence for established populations in the eastern Mediterranean is lacking. The relevance of these new additions of thermophilic fishes to the central Mediterranean ichthyofauna is discussed in relation to ongoing biotic changes in this sea.