What lurks underground, is miniature and resembles bhujia, a popular Indian snack, when preserved? A very special fish called the Bhujia eel loach.
Bhujia eel loach or Pangio bhujia, a new species of eel loaches described from the Southern Indian state of Kerala, is the first subterranean species of eel loaches. Pangio is a genus of freshwater fish in the loach family, and several of the loaches have become increasingly popular among aquarists.
Pangio bhujia was described by researchers and environmentalists from Kerala University of Fisheries and Ocean Studies, Natural History Museum, London, IISER Pune and Malabar Awareness and Rescue Centre for Wildlife, Kannur in a paper in the journal Zootaxa. Its discovery was triggered by a social media post thanks to a resident of Cherinjal village in Kozhikode, Kerala, who first spotted the eel-like fish.
With almost no eyes, very little pigment and the complete absence of its dorsal fin, the 25 mm fish is only the second miniature species in the genus and is now the 10th subterranean species from Kerala’s laterite areas.
Ralf Britz, a researcher at the Natural History Museum who co-authored the paper describing the species, said the eel-shaped fish has very long nasal barbels in addition to the other three pairs of barbels and has lost its pelvic fins. Barbels are long thread-like extensions around the mouth covered in taste buds.
“But the most unusual feature is the complete absence of its dorsal fin,” Britz told Mongabay. “It is not only the only Pangio without a dorsal fin, but also the only species of the order Cypriniformes [that is more than 4600 species] without a dorsal fin! We also found that several specimens were mature females with eggs that are twice the size of normal eggs of other eel loach species.”
Pangio bhujia is anatomically quite different from most other species of eel loaches and many of its characters could be seen in the context of its subterranean habitat.
“The tiny, worm-like body will make it easier to move around in the tiny confined spaces of its habitat, the laterite aquifers,” explained Britz. “The reduction of both the pelvic and the dorsal fins would also need to be seen in this context. The strong reduction of its pigmentation and reduction of its eyes are common adaptations to life in the subterranean darkness, in which neither is needed.”
Also, the comparatively large eggs would result in fewer but much larger larvae and juveniles, which may be better equipped to survive in a subterranean habitat where the food sources are scarce, as they would not need to eat as often as the tiny larval stages of the other eel loaches.
The photo posted on social media prodded study co-author Rajeev Raghavan, assistant professor at Kerala University of Fisheries and Ocean Studies to pursue the trail of the Bhujia eel loach.
“The discovery followed after I saw a photo of the fish being shared on social media [WhatsApp] of a bizarre-looking fish which was said to be collected from a well near the city of Kozhikode,” Raghavan told Mongabay. “I immediately contacted the person who shared the photos and sent my students to the location. They then stayed overnight at this location and could collect several specimens which were then studied in the laboratory for their morphological, anatomical and genetic characters.”
As for its naming, it all happened over breakfast in a coffee shop in Kerala, when Ralf Britz was having breakfast with two of his colleagues and he saw a row of packs of an Indian snack, which had on an image of its contents on the outside.
“It hit me and I said to my colleagues, ‘what is this, this looks like our new species of Pangio’,” said Britz. “They told me it is called bhujia, a common snack in India, to which I replied that this would be the perfect name for our new fish.”
This is because the individuals of this fish are tiny, one of the smallest Pangio species, and when preserved they are slightly curved.
The discovery of Pangio bhujia has once again spotlighted the subterranean fish fauna of Kerala, which Britz says is one of the most spectacular ones in the world.
There are a number of blind fishes in other parts of the world, but the ones here in Kerala are just strange and mysterious, he maintained, underscoring that the subterranean fauna in Kerala appears to be much more ancient than that of other regions in the world, in which you find fishes living underground.
“This is meant in the sense that they look very different from any other fish species that they may be closely related to,” Britz pointed out. “This would probably indicate that they becoming subterranean dates much further back than that of other subterranean fishes. If you look at a large number of Chinese subterranean fishes, these are still similar to their relatives that live above ground. For some of the Keralan subterranean species, we do not even know what their closest relatives are. This makes the Keralan fauna more interesting and enigmatic.”
However, the elation surrounding the discovery is not bereft of worry, that diminishing groundwater could endanger these fishes.
“The habitat of the eel loach comprises of a well and small wetlands that connect to the well,” noted Raghavan. “All of this is part of human settlements and the water is used for household purposes. There are no real threats in the habitat that can pose a danger to the fish in the immediate future but the decline of groundwater is a major concern in Kerala and it is likely that groundwater decline could lead to stress in these fishes.”
According to the researchers the next step for the Bhujia eel loach would be to figure out where they go on the eel loach tree, are they more closely related to the other Indian loaches or are their relatives in South East Asia?
How long have they been separated from their closest relatives? How do they live and reproduce in their subterranean habitats? What do they feed on? How long does it take them to mature?
“In a more general context, we need a better idea of what the aquifers in Kerala look like, how they are interconnected or not, which other fish species live in there that await their discovery?” wondered Britz. “Which are the biogeographic connections of the various animals that live in these aquifers? Is the aquifer habitat changing and is this the reason we have been discovering more species within the last few months since the first Kerala floods in 2018.”
“To answer some of these questions, Rajeev, other Indian colleagues and I hope we will be able to secure some funding to initiate an international project that will look in more detail at the unique subterranean fish fauna of Kerala,” added Britz.
This article first appeared on Mongabay.