"A few examples: The Cuban Cusk-eel (Bythitidae) Lucifuga subterranea Poey 1858 lives in the anchialine caves, sinkholes and crevices of Cuba. Its genus name, also coined by Poey, is a combination of the Latin lux, meaning light, and fugio, to flee, fly or take flight — i.e., fleeing light — referring to its subterranean (and therefore lightless) habitat.

Aspidoras mephisto Tencatt & Bichuette 2017 (Callichthyidae) is described from Anésio III cave in the Tocantins River basin of Goiás, Brazil. Its name refers to Mephistopheles, a demon from German folklore (me-, not; phos, light; philis, loving, i.e., not liking light). This catfish is the first troglobitic species known from its family (famous for the Corydoras catfishes popular in the aquarium trade). The netherword of Hell is evoked in the next two names.

Ophisternon infernale (Hubbs 1938) is a blind swamp eel (Synbranchidae) that inhabits freshwater in sinkholes and limestone caves in the Yucatán Peninsula of Mexico. Its specific name is from the Latin infernalis, of or belonging to the world or “regions” below the surface of the Earth — i.e., to the realm of the dead in ancient mythology, or the abode of evil spirits in Jewish and Christian belief.

The most-famous denizen of Hell, the Prince of Darkness, is evoked in the genus name of the Widemouth Blindcat (Ictaluridae), Satan eurystomus Hubbs & Bailey 1947, known only from aquifers deep below San Antonio, Texas.

The netherworld of Greek mythology, Styx, is evoked in the names of Stygichthys typhlops Brittan & Böhlke 1965, a blind cave tetra (Characidae) from the Juíba karst aquifer of Minas Gerais, Brazil. The specific epithet typhlops — from typhlos, blind, and ops, eye —refers to the lack of any external evidence either of eyes or of circumorbital bones (except for one short isolated segment).

To this list we can add this recently described eel loach (Cobitidae) from India: Pangio pathala Sundar, Arjun, Sidharthan, Dahanukar & Raghavan 2022 (shown here). Its specific name comes from the Sanskrit pâtâla, meaning “below the feet,” referring to its subterranean habitat. The loach was collected from an overhead water-storage tank connected to an old dug-out well at a house in Thiruvanvandoor, Chengannur, Kerala, India.



As reported in The Wire, an Indian nonprofit news and opinion website … https://science.thewire.in/.../pathala-eel-loach-citizen.../



… the owner of the house was taking a shower when he felt a “thread-like” thing fall from above. When he looked down, the “thread” moved. The owner placed the wriggling creature — barely the length of his little finger — in a small glass jar filled with tap water. Then he called researchers at Kerala University in Kochi who had been conducting workshops and door-to-door awareness campaigns about subterranean fishes in the area since 2017. The researchers found three more specimens in the 17-foot well that supplied water to the shower." - The ETYFish Project