A team of experts from the UK, Switzerland and India have discovered the world’s largest species of cave fish in Meghalaya’s Jaintia Hills.
The cave fish, similar in anatomy to an endangered mahseer species, is around one and a half feet in length and was found inside a remote cave in Jaintia Hills.
Details of the fish have appeared in a paper written by four researchers in the November 2019 issue of Cave and Karst Science.
The fish has no eyes and is white due to lack of melanin pigmentation.
When biologist Daniel Harries first saw the fish in an expedition in February last year, he was amazed.
“My first reaction upon seeing the fish myself was, I’m going to need a bigger net,” National Geographic quoted Harries as saying.
The fish may still be in the process of evolving to be a separate new species, he said.
There are 250 known species of fish found under the earth’s surface.
As they live in a nutrient-limited environment most of these species are small—195 of them have a mean length of 8.5cm. The only two species, which exceed 30cm, are eel-like and have very thin bodies.
“It has always been assumed that cave fishes exceeding 350mm (35cm) would be most unlikely on resource grounds but this has now been shown to be spectacularly wrong,” said the paper.
“The fish discovered in Meghalaya in February 2019 is not only substantially longer than the longest previously known species but is considerably more bulky with a body mass likely to exceed that of the next largest cave fish by at least an order of magnitude,” it added.
Researchers believe the fish is bulky in size due to large and regular food supply, with surface vegetation entering the cave through the entrance shaft on rainy seasons.
There appeared to be hundreds of similar fish in the cave.
“When first encountered the fish appeared unresponsive to light, although they did react to the water disturbance created by the cavers wading through the pools,” the researchers mentioned in the paper.
“Although it seems that they were initially unresponsive to light, they are certainly able to perceive light,” they added.
They further said the fishes initially showed no reaction to light for the first time but moved away when torchlight was shone on them again later.