The fish was found in Kerala, South India, and is the first snakehead fish that has been described as living underground, its shared subterranean existence with Gollum has been said to be the reason for its naming.
Snakeheads are native to Africa and Asia and are distinguished by their long dorsal fins, large mouths, and ability to breathe air using what is known as a suprabranchial organ in their gill cavity.
These fishes usually live in freshwater rivers or wetlands making this new discovery, living in an environment unlike any documented before, particularly exciting.
The species was discovered by chance after pictures of the fish were posted online following the devastating floods that hit Kerala in August last year.
The images prompted the Kerala University of Fisheries and Ocean Studies to investigate.
“As soon as I saw higher quality images it became pretty clear that it was a snakehead,” says Dr Ralf Britz from the Natural History Museum and co-author of the paper describing the new species.
“Having a snakehead from a subterranean habitat is an exciting find. This fish is very unusual.”
Globally subterranean fishes are mainly represented by only two groups, the catfishes and carps, as species in these groups are thought to be pre-adapted to life underground.
Snakeheads, however, don't tend to have any adaptations that might also be suited to an underground lifestyle.
“The surprising part is that - assuming it is subterranean - it doesn't have the typical adaptations you would expect from a subterranean fish,” explains Britz.
“Either the fish only acquired this subterranean mode of life recently, or it is living in some kind of transition zone where it is still moving between the underground and above ground habitats. We simply don’t know and so that is something we'd be very interested in finding out.”
The new fish is highly distinctive when compared the known snakeheads, it has an incredibly long, eel-like body; numerous scales, a very long anal fin running along its belly and tail and has lost the ability to maintain buoyancy in the water column.
This is now the eighth species of subterranean fish that has come out of the aquifers beneath Kerala, leading researchers to believe that there must be a hidden ecosystem existing over 40 metres below the surface.
In our August 2018 edition BBC Wildlife Magazine also covered a new species discovery named for a The Lord of the Rings character; Bilbo Baggins shrimp, named for its likeness to the hobbit with both sharing hairy feet, and in April 2017, BBC Wildlife Magazine reported on the discovery of Europe's first cave fish.
Main image: Aenigmachanna gollum. © Anoop V.K