Nemacheilus troglocataractus

Kottelat and Gery 1989

Nemacheilus troglocataractus
Drawing by Rhian Kendall from a photograph in Kottelat and Gery (1989)
CypriniformesCobitoidei Nemacheilidae






Holotype: MHNG 2407.54 67.7mm SL. Paratypes: MHNG 2407.55 2 specimens 55.2mm and 57.3mm SL; NIFI 2184 47.8mm SL; KUMF 2958 58.3mm SL; MNHN 1989-266 3 specimens 48.2mm ‑ 55.7mm SL; ZSM 26794 2 specimens 58.2mm and 61.3mm SL; CMK 5960 2 specimens 51.8mm and 59.7mm SL; CMK 5961 55.3mm SL cleared and stained.


Known only from the type locality: Tham Sai Yok Noi (also known as Tham Nam Tok and Tham Wang Ba Dan), 3km NNW of the village of Nam Tok, Sai Yok District, Kanchanaburi Province, Thailand (14o15'N, 99o4’E). The silurid Pterocryptis buccata has also been collected from this cave and the two species coexist. A troglophilic frog, Siamophryne troglodytes, is found in a cave in the same area (Suwannapoom et al. 2018).


A typical gravel-bottomed streamway with shallow perennial flow (Trajano et al. 2002). A description of the cave is provided by Brouquisse (1987) and the hydrogeology is described by Brouquisse and Dalger (1987). The cave atmosphere contains 5% carbon dioxide.


Possibly related to Nemacheilus mexicanus, N. masyae or N. pallidus (Kottelat 1990). In the subfamily Nemacheilinae.

Conservation Status

[CR B1ab(iii,v)+2ab(iii,v):3.1:2011]

(Vidthayanon, C. 2011. Nemacheilus troglocataractus. The IUCN Red List of Threatened Species 2011: Downloaded on 04 July 2017). R (IUCN 1990), R (IUCN 1993), VU D2 (IUCN 1996, 2000).

This species has only been recorded from one subterranean stream in the Sai Yok Noi cave. Its extent of occurrence (50-100 km²) and area of occupancy (ca. 1 km²) are both very restricted, and there has been an observed decline in habitat quality and number of individuals. It is therefore assessed as Critically Endangered.

Museum Holdings

As above plus: ZSM/CMK 5992 3 specimens 49.4‑55.5mm SL (Kottelat 1990).

Key References

Gery, J. Journal Article 1987 Note sur la faune pisciaire souterraine des Celebes et de Thailande
Brouquisse, R. Journal Article 1987 Resultats speleologiques Thailande
Brouquisse, F. and Dalger, D. Journal Article 1987 Hydrogeochimie
Kottelat, M. and Gery, J. Journal Article 1989 Nemacheilus troglocataractus, a new blind cavefish from Thailand (Osteichthyes, Balitoridae)
Kottelat, M. Book 1990 Indochinese nemacheilines. A revision of nemacheiline loaches Pisces, Cypriniformes) of Thailand, Burma, Laos, Cambodia and southern VietNam
Ng, H.H. and Kottelat, M. Journal Article 1998 Pterocryptis buccata, a new species of catfish from Western Thailand (Teleostei: Siluridae) with epigean and hypogean populations
Borowsky, R.L. and Vidthayanon, C. Journal Article 2001 Nucleotide diversity in populations of balitorid cave fishes from Thailand
Deharveng, L. and Bedos, A. Book Section 2001 Thailande
Trajano, E., Mugue, N., Krejca, J., Vidthayanon, C., Smart, D. and Borowsky, R. Journal Article 2002 Habitat, distribution, ecology and behaviour of cave balitorids from Thailand (Teleostei: Cypriniformes)
Kottelat, M. Journal Article 2012 Conspectus cobitidum: An inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei)
Duboue, E.R. and Borowsky, R. Journal Article 2012 Altered rest-activity patterns evolve via circadian independent mechanisms in cave adapted balitorid loaches
Brancelj, A., Boonyanusith, C., Watiroyram, S. and Sanoamuang, L. Journal Article 2013 The groundwater-dwelling fauna of Southeast Asia
Suwannapoom, C., Sumontha, M., JTunprasert, J., Ruangsuwan, T., Pawangkhanant, P., Korost, D.V. and Poyarkov, N.A. Journal Article 2018 A striking new genus and species of cave-dwelling frog (Amphibia: Anura: Microhylidae: Asterophryinae) from Thailand
Anonymous Journal Article 2018 Scientists found a new genus and species of frogs
Ellis, M. Journal Article 2018 The recorded fauna of the limestone caves of Thailand to April 2018
Ellis, M. Journal Article 2020 The caves of western and central Thailand