Meet Kryptoglanis shajii, a subterranean species of catfish that was described only a few years ago. It is endemic to the Western Ghats in India; an area known for its incredible biodiversity. However, for a creature that lives among so many other species, scientists are having an incredibly difficult time finding the fish’s place in all of it. John Lundberg of Drexel University, who is one of the world’s leading experts in catfish, has been studying the fish since its discovery. Though many aspects of K. shajii defy classification, Lundberg’s latest analysis has focused on the bone structure of this freaky fish. The results of the study were published in the Proceedings of the Academy of Natural Sciences in Philadelphia.

Lundberg and his team used CAT scans and digital radiography to get a detailed look at the skeleton of this small fish, which had some anomalies that weren’t very obvious from the outside. “The more we looked at the skeleton, the stranger it got,” Lundberg said in a press release. “The characteristics of this animal are just so different that we have a hard time fitting it into the family tree of catfishes.”

Though many subterranean fish lack certain bony features, K. shajii has bones with morphologies that Lundberg doesn’t recognize among catfish or any other group of fish. The fish itself has a face that looks kind of smushed flat, like a bulldog. This shape must have come about due to some incurred benefit, but researchers aren’t sure what that could have been quite yet. “In dogs that was the result of selective breeding,” Lundberg explained. “In Kryptoglanis, we don’t know yet what in their natural evolution would have led to this modified shape.”

The fish have four rows of sharp conical teeth, which researchers believe are used to eat small invertebrates and insects. The fish itself is relatively small at less than ten centimeters long and it is very quick and agile.

A specimen of Kryptoglanis shajii that was scanned in Lundberg's team's study. Credit: Kyle Luckenbill, Academy of Natural Sciences of Drexel University

In addition to what has caused this odd facial shape, researchers aren’t exactly sure where the fish fits in with others, as there are no obvious candidates to closest living relative. DNA analysis isn’t that revealing, because individuals within this species, as with many catfish species, have shown to have drastically different sequences, which isn’t particularly helpful when trying to compare with other fish.

At the same time that Lundberg’s team was analyzing the bone structure using CAT scans and digital radiometry, Ralf Britz and his team from the Natural History Museum of London were investigating the skeleton through staining. The results from the London team, which were published in Ichthyological Exploration of Freshwaters, were remarkably similar to Lundberg’s team. Neither group was able to determine what the relatives to this fish might be, and the London team even suggested that it belonged to its own family.