New Eel Species Found After TikTok Tipped Off Scientists

This Tiny, Pale Eel Is the First of Its Kind to Live Its Whole Life Underground

Scientists discovered a tiny, nearly pigment-free eel living in underground water beneath the Gangetic Plain in northern India after a TikTok video tipped them off to its existence. Barely longer than a standard crayon, this creature had been hiding in the dark, water-filled spaces beneath one of the most densely populated and heavily farmed regions on Earth, completely unknown to science. Researchers had to pump thousands of liters of water from rural borewells, machine-drilled shafts that tap into groundwater, just to catch a glimpse of it.

Formally named Gangaichthys indonepalicus and described in the journal ZooKeys, the fish belongs to a group of tiny freshwater eels called earthworm eels, a family known for being small, secretive, and rarely seen. No member of this family had ever before been found living underground. Every other known earthworm eel burrows in mud or plant debris in surface swamps, ponds, and streams. This one lives entirely beneath the earth, in water-filled gaps within sediment layers, making it the first of its kind to truly live a subterranean life.

A TikTok Video Led Scientists to Bihar’s Borewells

The research team first spotted that TikTok video in 2024. Based on the animal’s appearance, researchers suspected it might be something entirely new to science. They organized expeditions in 2024 and 2025 to the Indo-Gangetic Plain in Bihar State, India, to try to find it.

Locating the fish proved enormously difficult. Researchers sampled more than 15 wells over roughly a week of hand-pumping. They recovered just three specimens from two separate wells. One came up alive and intact, one was damaged during pumping and died immediately, and a third, from a well about a kilometer away, was recovered in fragments.

Collecting the intact animal and the damaged specimen from a single well required pumping out approximately 2,000 to 2,500 liters of water. That effort, for a fish barely over 40 millimeters long, speaks to just how deeply hidden this creature is from the surface world.

Darkness Stripped Away Its Eyes, Color, and Ribs

Animals adapted to permanent darkness underground tend to show a familiar set of traits: reduced eyes, loss of skin pigment, and other structural reductions. Researchers describe these shifts as a common outcome of relaxed evolutionary pressure in dark, resource-scarce habitats, arising independently across many unrelated underground species rather than pointing to any close relationship between them.

Gangaichthys indonepalicus fits this pattern closely. Its body is pale and nearly see-through, with no pigmentation at all, and its eyes are tiny and covered by skin. CT scans revealed no visible ribs, though the scans were performed without contrast agents, meaning faint or cartilage-based structures may not have shown up. Researchers describe this as an apparent absence of ribs rather than a confirmed one. In life, the fish appeared pale and translucent, with pinkish patches near the gills and a faint pink line along its tail where blood vessels showed through the skin. In preservative, it faded to off-white.

DNA and Bone Scans Confirmed an Entirely New Genus

Because only one intact specimen was available, the team used every tool at their disposal to document it. Measurements were taken under a stereo microscope, internal scans captured the arrangement of tiny bones, and DNA was extracted from the intact fish and one damaged specimen, with two segments of genetic code sequenced and compared against known relatives.

Genetically, Gangaichthys indonepalicus sits firmly within the earthworm eel family, but is clearly distinct from its closest known relatives, differing by more than 20% in the genetic marker most commonly used for fish identification. Comparative data for this family is scarce: only two other earthworm eel species had usable sequences, and no comparable nuclear DNA data existed at all.

Physically, the fish is distinctive too. It has 64 total vertebrae, a count matching no other known earthworm eel species, and unique fin structure, including a single ray in its chest fin rather than the several other family members carry. Its name, Gangaichthys, combines the Sanskrit word for the Ganges River with the Greek word for fish. Its species name, indonepalicus, reflects photographic records from Nepal, just across the border, suggesting the fish lives there too.

Groundwater Extraction Puts Hidden Species at Risk

Finding a new species is always cause for celebration in science. But researchers point out something worth sitting with: this fish turned up in underground water beneath one of the most intensively used groundwater regions on Earth. Agricultural demand across the Gangetic Plain has driven massive, ongoing groundwater extraction, and farm chemical contamination is a documented concern.

According to the paper, targeted surveys for underground fish are needed across India, where high extraction and contamination likely already affect animals that, unlike fish in rivers or lakes, have nowhere else to go. Its discovery raises an uncomfortable question about what groundwater pumping may be doing to species barely documented before they disappear.

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