New alien fish and sea urchin species have been spotted in the waters of the Aegean this month, the Archipelagos Institute of Marine Conservation in Greece has reported.

A diver from the institute, Eugenios Loudaros told Kathemerini that he had seen concentrations of the Indian Ocean two-spot cardinalfish (Cheilodipterus novemstriatus) several times in waters to the east of the island of Rhodes and at a depth of 8 to 9 metres.

Mr Loudaros also identified in the same waters another alien species,  the long-spined sea urchin (Diadema setosum).

The two-spot cardinal fish is normally found in the Pacific and Indian Oceans. Its presence in the Mediterranean was first reported in 2010 and it is believed the fish came through the Suez Canal. The first sightings were off the coast of Israel but it has since been seen in Lebanon, Turkey, Cyprus and Syria.

READ MORE: Greek researchers to conduct research into potential of invasive fish species

The fish which lives in groups of up to 30 is between 2cm and 8cm long and feeds mainly on zooplankton.

“The location of a new alien species in Greek waters underlines the continuing process of entry and residence in the Mediterranean of species from other, warmer, seas,” said Anastasia Miliou, a hydrobiologist and research director at the institute.

“This is because they find gaps in the ecosystem, gaps that have been caused by our own activities, whether they are related to overfishing and the destruction of the marine environment or climate change, which leads to rising water temperatures and therefore makes them more hospitable to invasive species.”