Marine biologists being filmed for a BBC TV series about the ocean have managed to find no less than 13 species of fish previously unknown to science. The group also reports having 15 other animals in their possession that they suspect to be new species.

The newfound species have been gathered during deep reef dives in Micronesia in the Pacific Ocean during explorations of the so called “twilight zone”. Located at a depth of 60 to 150 meters (500 to 200 feet), the twilight zone forms a transitional region between sunlit shallow waters and the perpetually dark depths of the sea.

One of the findings is of special importance to marine aquarists – a new species of damsel fish. Damsels are very popular among saltwater fish keepers since they are one of the most robust groups of marine fish and generally adapt well to a life in aquaria. The new damsel species was caught 120 meters down off Palau and sports a bright blue colouration.

The bright blue damsel was actually spotted over a decade ago by Dr Richard Pyle, and it has been occasionally seen since then by other researchers as well, but it was during the BBC filming that the species could be captured and brought up to the surface for scientific examination for the very first time. The fish has now been scientifically described and named by Dr Pyle from the Bishop Museum, Honolulu, Hawaii.

Recreational scuba divers with ordinary scuba gear are not advised to venture any deeper than 40 meters (130 feet), so the researchers of this expedition had to use special closed-circuit rebreathers to access the twilight zone. Even with rebreathers, you quickly run out of air at such a great depth and there is no time for any meticulous investigation of the environment.

The expedition will be portrayed in the BBC series “Pacific Abyss” and the new species of damsel have been appropriately named Chromis abyssus.

Pacific Abyss starts its three-part run on Sunday, 17 August, on BBC One, at 2000 BST.

Video from the dives