Cryptotora thamicola

(Kottelat 1988) Kottelat 1998

Cryptotora thamicola
Illustration by Rhian Kendall from a photograph in Kottelat (1988)
CypriniformesCobitoidei Balitoridae


Homaloptera thamicola  Kottelat 1988




Holotype: AMS I.25987‑001 28.4mm SL. At the time of its description this was the only known specimen and no other types were assigned.


Type locality: Tham Susa, Pang Ma Pha District, Mae Hong Son Province, Thailand (19o28'N, 98o08'E). Known also from Tham Mae La Na in the same province where it coexists with Schistura oedipus (Richard Borowsky pers. comm.).


Within Tham Mae La Na this species is found in water cascading over flowstone while its co-inhabitant, Schistura oedipus, lives in gour pools and other lentic habitats. The two species seem to strictly partition the habitats (Trajano, Mugue, Krejca, Vidthayanon, Smart and Borowsky 2002).  The population size is of the order 102 – 103 which is very small (Trajano, Mugue, Krejca, Vidthayanon, Smart and Borowsky 2002).  


Kottelat (1988) discussed various aspects of the relationships of this species but commented that he was in the process of researching this and would present a fuller analysis at a later date. Kottelat (1998) provides the replacement generic name Cryptotora since there are a number of differences separating this fish from others in the genus Homaloptera. Data on pigmentation and behaviour collected by Trajano, Mugue, Krejca, Vidthayanon, Smart and Borowsky (2002) suggests that this species is a palaeo-stygobite.

A detailed study of the skeletal and muscular morphology of Balitoridae in southern Asia by Crawford et al. (2020) demonstrated that Cryptotora thamicola is sister species to a group containing the genera Homaloptera, Balitoropsis, Pseudohomaloptera, Balitora, Hemimyzon and Sinogastromyzon.

Biological Notes

Eyes absent, pigment absent (AB/AB phenotype of Farley (2021), see also Metadata section for more details of this classification).

Conservation Status

MG [VU B2ab(iii) D2:3.1:2011]

VU B2ab(iii) D2:3.1:2011. (Vidthayanon, C. 2011. Cryptotora thamicola. The IUCN Red List of Threatened Species 2011: Downloaded on 06 July 2017). The species has been recorded from eight subterranean sites within a large karst system (Pang Mapha karst formation) in Mae Hongson Province, Thailand. The species has an Extent of Occurrence of nearly 200 km2, but and Area of Occupancy of 6 km2. The connectivity of this karst sytems is unknown, some caves are definitely connected. The species is found in eight locations based on the current threat to the species (habitat degradation by cave tourism). Therefore the species is assessed as Vulnerable. However the species has a potential threat of agricultural pollution which could impact the whole karst system, making it one location. If this was to impact the species it would qualify for Critically Endangered. It may also occur in other caves in the area. VU D2 (IUCN 1996, 2000).

Museum Holdings

As above only.

Internet Resources

Cryptotora climbing a waterfall with its unique fins

Video of Cryptotora in its natural habitat

Images of Cryptotora

Key References

Kottelat, M. Journal Article 1988 Two species of cavefishes from northern Thailand in the genera Nemachilus and Homaloptera (Osteichthyes, Homalopteridae)
Kottelat, M. Journal Article 1998 Homaloptera yuwonoi, a new species of hillstream loach from Borneo, with a new generic name for H. thamicola (Teleostei: Balitoridae)
Deharveng, L. and Bedos, A. Book Section 2001 Thailande
Borowsky, R.L. and Vidthayanon, C. Journal Article 2001 Nucleotide diversity in populations of balitorid cave fishes from Thailand
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)
Prokofiev, A.M. Journal Article 2010 Morphological classification of loaches (Nemacheilinae)
Kottelat, M. Journal Article 2012 Conspectus cobitidum: An inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei)
Brancelj, A., Boonyanusith, C., Watiroyram, S. and Sanoamuang, L. Journal Article 2013 The groundwater-dwelling fauna of Southeast Asia
Lujan, N.K. and Conway, K.W. Book Section 2015 Life in the fast lane: A review of rheophily in freshwater fishes
Sherwin, F. Web Page 2016 Wall-climbing cave fish: Evolutionary intermediate?
Zimmer, C. Web Page 2016 Researchers find fish that walks the way land Vertebrates do
Flammang, B.E., Suvarnaraksha, A., Markiewicz, J. and Soares, D. Journal Article 2016 Tetrapod-like pelvic girdle in a walking cavefish
Ellis, M. Journal Article 2018 The recorded fauna of the limestone caves of Thailand to April 2018
Anonymous Web Page 2018 New walking cavefish study explores origins of quadrapedal walking
Anonymous Web Page 2018 First steps. Scientists launch evolutionary study to explore the origins of fish that walk
Anonymous Web Page 2018 New walking cavefish study explores origins of quadrapedal walking
Liew, J.H., Chua, K.W.J., Arsenault, E.R, Thorp, J.H., Suvarnaraksha, A., Amirrudin, A. and Yeo, D.C.J. Journal Article 2019 Quantifying terrestrial carbon in freshwater food webs using amino acid isotope analysis: Case study with an endemic cavefish
Willis, J., Burt de Perera, T., Newport, C., Poncelet, G., Sturr, C.J. and Thomas, A. Journal Article 2019 The structure and function of the sucker systems of hill stream loaches
Ellis, M. Journal Article 2020 The caves of northern Thailand
Zhongming, Z., Linong, L., Xiaona, Y., Wangqiang, Z. and Wei, L. Web Page 2020 Study of Asia's hillstream loaches reveals keys to fish family's land-walking abilities
Crawford, C.H., Randall, Z.S., Hart, P.B., Page, L.M., Chakrabarty, P., Suvarnaraksha, A. and Flammang, B.E. Journal Article 2020 Skeletal and muscular pelvic morphology of hillstream loaches (Cypriniformes: Balitoridae)
Crawford, C.H. Thesis 2021 These fish were made for walking: morphology and walking kinematics in balitorid loaches
Crawford, C.H., Webber-Schultz, A., Hart, P.B., Randall, Z.S., Cerrato-Morales, C., Kellogg, A.B., Amplo, H.E., Suvarnaraksha, A., Page, L.M., Chakrabarty, P. and Flammang, B.E. Journal Article 2022 They like to move it (move it): walking kinematics of balitorid loaches of Thailand
Flammang, B.E. Journal Article 2022 Bioinspired design in research: Evolution as beta-testing