Several years ago a colleague sent me two specimens of blind cave fish collected in the Zagros Mountains of western Iran. I was intrigued. The specimens were small, just 2.5 centimetres long, and in very bad condition. But I could tell they belonged to the cyprinid genus Garra — and there were hints they are probably a new species to science. But, we’ll probably never know, and to explain why requires some background context.
Cave fishes are fascinating creatures whose habitat is usually the water in limestone caves, including tiny cracks between rock layers, and often occurring over very wide areas. Blind cave fish are related to species living in nearby streams and rivers. But, in the absence of light deep underground, there’s no advantage in maintaining eyes and sight. They’ve also lost skin pigmentation, appearing pink, a result of blood visible through their unpigmented skin. The blind cave fishes are thus different species, clearly defined by their DNA.
Four species of blind cave fishes are known to exist in the Loven and Tashan caves in Iran, including three members of the Cyprinidae family (carps) and one of the Nemacheilidae family (loaches). However, these sites are respectively about 130 and 270 km away from where the new specimens were collected, heightening the possibility the specimens represented a new species.
Since the specimens were in poor condition, the only way to solve the mystery was to collect more. Unfortunately, this is no longer possible. They were collected from a shallow pool formed from water seeping from a rock face when a tunnel was drilled through a mountain during construction of the Simareh dam in 2005. The tunnel where they were collected in now buried, encased in concrete.
Faced with this dead-end, we thought we might be able to solve the question by examining the DNA of the specimens and comparing it to that of known Iranian cave fishes DNA available in an online database. Despite the valiant efforts of the museum’s DNA specialist Roger Bull, this route also failed. The fishes’ genetic material was damaged beyond recognition by time and its initial preservation in formalin.
Thus, it appears that this possible new species of blind cave fish may have been lost to science before it was truly found.
Yet, ironically, currently buried under hundreds of metres of rock and concrete, it may now be safe from any further ravages, whether natural or human-caused.