Kerala hotspot of subterranean fishes

Of the known eight subterranean fish species, six are inhabitants of the State

April 24, 2017 12:56 am | Updated June 12, 2021 01:49 pm IST - Thrissur

They may look like baby snakes. But they are actually fishes.

Kerala is the ‘hotspot of Indian subterranean fishes, say scientists. Fishes, which live in the underground water bodies are called subterranean fishes.

Of the eight subterranean fish species known from the country till date, six are inhabitants of the dugout wells of Thrissur, Malappuram, Kottayam, Pathanamthitta, Kozhikode and Kannur districts in the State, says V.V. Binoy, Assistant Professor, National Institute of Advance Studies, Bangalore.

“Generally these fishes appear in the wells either during summer, when the wells dry up, or with the onset of monsoon. Unfortunately due to the close resemblance with snakes in shape, colour and pattern of movement, people get scared and often kill them as soon as they are spotted.” However, they are non-poisonous and harmless and their presence is essential to maintain the health of the ground water ecosystem, Dr. Binoy noted.

These fishes are a treasure to science to understand the evolution and biography. Very few studies have been conducted till date on these cryptic fish species, scientists noted.

There are many species of fishes surviving in extreme conditions of subterranean ecosystems, which look like strange organisms, according to studies.

Fishes live in the underground water bodies have reduced or absence of eyes and hence depend on their sense of smell and vibrations to move through their surroundings and to find food and mate. Their colouration is also unique; some are pinkish red, some brown and even black. Many species don't even look like fishes but would rather resemble an earthworm or a baby snake.

“Interestingly, many of these fishes have counterparts living in the open water bodies with fully developed eyes and fins. The genetic relatives of many of the known subterranean fishes have been reported from locations, which are thousands of kilometers away – some even in other continents,” studies point out.

However, due to the large-scale reclamation of water bodies, overexploitation of ground water resources and introduction of the exotic predatory species like African catfishes into the wells, these fishes are moving towards ‘silent extinction’. Chlorination of wells using bleaching powder, especially during the summer periods when the water level comes down, is another factor which increases the pace of the extermination of these fishes.

Although many countries have already documented diversity of subterranean fishes, such studies have gained momentum only in the recent past in India.

Recently a team of scientists from the National Institute of Advanced Studies (NIAS) Bangalore, Kerala University of Fisheries and Ocean Science (KUFOS) and Nirmalagiri College, Kannur, has started documenting the fishes and other organisms surviving in the subterranean ecosystems of Kerala.

The team was not only able to collect the subterranean fishes but also species of shrimps and amphibians living in these environments. These scientists are involved in developing long-term strategies to protect and conserve the subterranean organisms which are facing a high risk of extinction.

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