Scientists have discovered the world’s largest known subterranean fish in a cave in northeastern India.

The “troglomorphic fish” was discovered last year, according to recently released research. “The largest individual seen in the cave was in excess of 400 mm [15.8 inches] in standard length making it, by far, the largest known subterranean fish found to date,” scientists explain in an abstract of the study.

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One of the fish that was discovered in a cave in northeastern India. (Uros Aksamovic)

The discovery of the blind fish challenges previously held theories on fish dwelling in subterranean locations. “It has always been assumed that cave fishes exceeding 350 mm would be most unlikely on resource grounds but this has now been shown to be spectacularly wrong,” the researchers explain. “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.”

The fish is similar anatomically to the Tor Putitora, an endangered Asian fish, which is also known as the Putitor Mahseer or Golden Mahseer fish. However, the cave fish discovered in Meghalaya differs from the Tor Putitora in its “depigmentation, lack of eyes and in its subterranean habitat,” according to the new research.

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The newly discovered fish is the largest known subterranean fish. (Uros Aksamovic)

The international team of researchers published their study in the British Cave Research Association’s Cave and Karst Science.

Daniel Harries, Ph.D., an assistant professor at Heriot-Watt University in Scotland and the study’s lead author, told Fox News that the size of the fish is significant. “It was generally assumed that since food is scarce in caves then animals like fish would be limited to a small body size and occur in relatively low populations,” he explained via email. “But here we have a fish that is more than 10 times bulkier than other species of cave fish and we probably saw around 100 individuals in this one cave. This throws up all sorts of questions such as what food source is sustaining them. We don’t have any clear answers for this yet but it is all very intriguing.”

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Researchers say that the largest of the fish discovered in the cave is more than 400mm [15.8 inches] in length. (Daniel Harries)

Harries said that it is also significant that the fish has remained undetected for so long. “Systematic exploration of the Meghalayan caves has been underway for almost 30 years and hundreds of kilometers of cave passages have been explored and mapped,” he explained. “Nevertheless, this very large cave fish remained undocumented until last year. This raises questions about what else might have been overlooked in the caves. “

Follow James Rogers on Twitter @jamesjrogers.