Scientists in Kerala discover four new subterranean fishes with help from residents

Subterranean fishes are ancient, having survived since the dinosaur era, and their study can contribute to insights into evolution history.
Pangio pathala
Pangio pathala
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Aiswarya, now a microbiology graduate, was a degree student when she found a ‘red creature’ in a pipe at her home in Kerala’s Chengannur of Alappuzha district. She preserved it in a bowl and shared the news with her professor, and her curiosity led to the discovery of a new species of subterranean fish in 2020.

“It was in the morning that I got a ‘creature’ after I opened up a pipe. It moved really fast so I just put it in a bowl out of curiosity, but had no idea it was a fish. I shared a photo with my professor, and he contacted the  Kerala University of Fisheries and Ocean Studies (KUFOS). They collected the fish after three days,” Aiswarya recollected. The fish that she found was Horaglanis populi, a small, blind, air-breathing catfish. 

Scientists at KUFOS have been studying 13 species of subterranean fishes with help from local residents in different districts in Kerala. Out of these 13, four are new discoveries – Aenigmachanna gollum, Pangio pathala, Horaglanis populi, and Pangio bhujia.

In the case of normal fishes, samples for research can be collected using nets from any lake or river with the permission of the authorities. Subterranean fishes can only be found in caves and underground habitats within private properties like wells or paddy fields. “Finding subterranean or underground fishes is tough for a scientist. It is unlike a normal fish, where we go with a fishing net and collect specimens. There is no direct access to the a subterranean water body also as they are hidden from our view, and they sometimes open through wells or paddy fields which are mostly situated in private lands,” Rajeev Raghavan, Assistant Professor at KUFOS and the head of the subterranean research team said. Therefore, studies of subterranean fish are not possible without the help of local residents, unless scientists find samples accidentally, like Aiswarya did. However, detailed research demands several samples and not just accidental finds.

Why do subterranean fishes need to be studied?

These fishes are small in size and found in dark, underground environments like caves and aquifers.. An important characteristic is the complete absence of, or their underdeveloped eyes because of their long-term adaptation to dark habitats. 

In Kerala, subterranean fishes are mostly found in aquifers and caves associated with the laterite regions.. The access to caves is comparatively easy for scientists.Laterite zones in Kerala are present in every district, except Wayanad, Idukki, and Palakkad, and the greatest number of subterranean fishes are often found in this area.

Rajeev, who is also the first Asian recipient of the Fisheries Society of British Isles (FSBI) Medal in 2022, explained that subterranean fishes are ancient and evolved in the geological eras when dinosaurs’ roamed the earth. “Unlike dinosaurs and other ancient animals, subterranean fishes have not did not gone extinct because of the isolated underground system where they live. So, these species can contribute to the study of evolutionary history of our planet,” he added, underlining the importance of studying subterranean fishes.

How do common people find subterranean fishes?

20-year-old Safwan found a subterranean fish when he was 17 years old, through his 6-year-old nephew in Malappuram’s Kottakkal, who collected it from the lakeside and thought it was a baby eel. Safwan identified it as an underground fish because he had an interest in fish, and had read about such subterranean species before. “Everybody thought it was a baby eel, but I felt it was not because of its reddish colour and underdeveloped eye. Then I Googled it and found a YouTube video, and commented on the video, and KUFOS scientists contacted me,” said Safwan, who is now a BSc aquaculture student at the MES Asmabi College in Kodungallur.

The fish Safwan found was discovered by KUFOS scientists as Pangio bhujia, a new species. “I caught this fish in 2020. In 2014, I got the same species from our well, but I was not aware it was an underground fish and put it in a fish tank. It did not survive,” he added.

Abraham, a 55-year-old ex-serviceman has another interesting subterranean fish story to share, of how his routine shower in 2020 led to the discovery of a fish, as well as became an international news item after two years. “I got it from the washroom while I was taking a shower. I noticed a thread-like creature and suddenly recalled a newspaper report about underground fishes. I poured some water on the fish and it started to move, and then I shifted it to a mug. Then I contacted a professor I know personally, and they contacted KUFOS,” he explained. The fish he discovered was Pangio pathala and in June 2022, Hollywood actor Leonardo DiCaprio shared a news story about Abraham, which was also covered by several other media outlets.

Vinaya, a homemaker from Veliyanad in Ernakulam also has a similar story of accidentally finding a reddish creature in September 2023, and the fish was identified as Horaglanis populi.“I drew water for cooking in the morning from the well and found a red creature that looked like a centipede, and called my husband. I was afraid that the water had been rendered poisonous because that was the first time I had noticed such a thing. But my husband had seen news reports and videos on the internet related to these fish and how common people found such fish. He called a fisheries coordinator and the KUFOS scientists came to our home and collected the fish,” Vinaya said. 

Vinaya also added that the KUFOS officials conducted a 30-minute session for people in the neighbourhood about the importance of this fish and what to do if they find it by accident. “A few of my neighbours said they noticed this before but did not know it was a fish. The scientists from KUFOS assured that the water is pure and that these fishes are only found in clean, uncontaminated water,” Vinaya added.

The role of citizen scientists

Citizen science is a branch of scientific study that is conducted in collaboration with the general public, especially residents of an area who are not professionals in the field, and those who participate in the study are known as citizen scientists. KUFOS unofficially began its citizen science program in 2015 by spreading awareness among common people and officially launched it in 2019 as a government project under the Kerala State Directorate of Environment and Climate Change. It was a two-year project but is still in continuance.

According to Rajeev, Kerala is the only state in India where a larger with the greatest number of subterranean fishes in the country are present, and it is important that the state initiates awareness drives for common people so that if a fish is found in an area, neighbouring residents can notice and help scientists collect more specimens for research. But people who notice subterranean fish in their wells usually panic and chlorinate the well for fear of contamination. Making people understand why this practice is wrong, and urging them to contact KUFOS was not an easy job for Rajeev and his team.

“In the initial stages, we got some samples accidentally and we conducted citizen science campaigns in the areas from where the fish were found through local Panchayat and Health departments. First, we address the misconception about the appearance of fish in their wells. Most people thought this new creature appeared because the water was contaminated. But the truth is that if this fish is present in your well, that means the water is purer than you think because they cannot survive in contaminated water”, Rajeev explained. Remya Sundar, a researcher in Rajeev’s team, said that this requires constant work. “ In Thrissur’s Amballur, we got a subterranean fish from a home and the people were not ready to use their wells after that out of the fear of contamination. We explained to them and finally, we drank the water ourselves to convince them,” Remya recalled. 

Rajeev added that these fishes have survived for millions of years because there are lesser impacts in the underground ecosystem, unlike rivers and lakes. But this also means that such fishes are more sensitive, and chlorination will lead to their death.

Now, the scientists have a WhatsApp group in different areas for people to share information after finding the fish. This also helps to address specific queries and alleviate misconceptions. “We are also connecting with the people who clean wells. We showed microscopic images of the fishes to them and have requested them to inform us if they find anything while cleaning the wells,” Rajeev added.

Remya stated that the pressure of the motor pumps used in cleaning wells prompt the fish to accidentally come up from their subterranean holes. Nonetheless, she added that the chance of getting them is exceptionally low, and genetic work has been done only of the available specimens. “We have not done breeding because of the lack of numbers. We need a female and a male for breeding, and additionally, we have several other research procedures like morphology,morphological, anatomical and molecular genetic investigations, etc. After all these processes, the specimen will dieTo undertake these studies, we need to sacrifice the fish,” Remya said.

“We cannot go to a home and ask people to search for fish, so a practically feasible way is to make them understand the importance of these organisms. That is what we have been doing for the last few years and nowadays, it is easier compared to the initial stages of this program. The news has also helped us because people like to see their names in newspaper reports and it gives other people an understanding of such fishes,” Remya added.

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