cave fish
April 5, 2017

First-ever European cave fish discovered by amateur diver

The pink, scaleless and possibly blind cave loach is the first ever instance of a fish found living in a European cave, and those behind the discovery said it is most northerly species of cave fish ever found.

According to a report on the discovery in the journal Current Biology, the cave loach likely split off from surface-dwelling loaches at within the last 20,000 years.

The fish was first sighted in a difficult-to-reach section of a subterranean water system in Southern Germany by amateur diver Joachim Kreiselmaier, who snapped a photo of the fish and passed it along to Jasminca Behrmann-Godel, an expert in fish evolution at the University of Konstanz in Germany.

"When I saw the photo I wasn't sure it was really something special," Behrmann-Godel told BBC News. "Then he brought me a live specimen and that was like the bang. That was the moment we realized that this was something really new!"

Relatively Young Creature

Divers have since retrieved five specimens for study, and genetic analyses have revealed the fish came about recently, within the last 20,000 years. Although scientists said they weren’t sure if it will ultimately be classified as a new species.

"The cave fish was found surprisingly far in the north in Southern Germany," Behrmann-Godel said in a statement. "This is spectacular as it was believed before that the Pleistocene glaciations had prevented fish from colonizing subterranean habitats so far north."

The eyes of the cave loach are much smaller than their surface-dwelling counterparts and their color is almost gone.  The study team said they do not react to light, suggesting they might be blind.

The researchers gave a lot of credit for the discovery to Kreiselmaier, the amateur diver who first spotted it.

"It took someone with the 'right eye' to realize that this might be something special and I believe that, on top of the right conditions and the difficult trip, this discovery depended on an exceptional diver like Joachim to realize in the first place that the fish might be special," Behrmann-Godel said.

"No more than 30 divers have ever reached the place where the fish have been found," Kreiselmaier noted. "Due to the usually bad visibility, strong current, cold temperature, and a labyrinth at the entrance, most divers do not come back again for diving."

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Image credit:  Jasminca Behrmann-Godel