Clarias cavernicola

Trewavas 1936

Clarias cavernicola
Redrawn by Rhian Kendall from Trewavas (1936)






Lectotype: BMNH 1935.3.20:174 145mm TL. Paralectotypes: BMNH 1935.3.20:175‑178 118mm ‑ 147mm TL. These types were assigned by Teugels (1986:134‑137) and are taken from the syntype series of Trewavas (1936). Trewavas records that the species was described from six animals but this is a mistake. The BMNH collection contains only five type specimens and they are the ones used by Teugels.


Known only from the type locality: Aigamas (or Aigumas) Cave, north of Otavi, west of Grootfontein, Namibia (19o26’30”S, 17o17’26”E). A very large lake in Dragons Breath Cave in the same area has been examined by divers but no sign of this species was seen (Maxwell 1988; Irish 1992). There is a film available on the internet which suggests that this species is known from Dragons Breath Cave but this is erroneous and should be diregarded (Gerald Favre and Alessio Fileccia pers. comm.). Despite this error it is worth watching the film for the last few moments as the fishes are beautifully portrayed.


The pool is in total darkness and is 18m by 2.5m in area, its depth is 30-52m although the fishes appear to live over shelves in shallow water up to 15m in depth (Jacobs et al. 2019). The water temperature is 27oC. The food supply consists of insects associated with bat and baboon guano and insects from carcases of dead animals (Skelton 1990a,1990b,1990c; Bruton 1995). The cave is inhabited by a large colony of the bat Hipposideros commersoni (Churchill, Draper and Marais 1997). The lake is also home to an endemic troglomorphic Isopod Namibianira aigamasensis Kensley 1995. The cave is described in detail by Sefton et al. (1986).


Trewavas (1936) suggested that the species was related to Clarias alluaudi Boulenger 1906, C. submarginatus Peters 1882, and C. dumerilii Steindachner 1866. After a very thorough study of all of the African species in the genus Teugels (1986) placed C. cavernicola in the subgenus Anguilloclarias together with the first two species named above. Also related to C. cavernicola are C. theodorae Weber, 1897 and C. nigromarmoratus Poll, 1967. The former of these two is particularly interesting as its range, in the Cunene and Okavango drainage basins, is adjacent to the Aigamas Cave, the home of C. cavernicola. C. dumerilii is not closely related as it differs in several important subgeneric characters.

Conservation Status

TLO [CR B1ab(iii)+2ab(iii):3.1:2007]

Bills, R. 2007. Clarias cavernicola. The IUCN Red List of Threatened Species 2007: Downloaded on 07 July 2017). E (Miller, 1977, E (IUCN, 1988), E (IUCN, 1990), E (IUCN, 1993), CR B1+2c,E (IUCN, 1996, 2000), CR B1ab(iii)+2ab(iii), E (TW). Endangered (Skelton 1990a,1990b,1990c). The lake in Aigamas Cave has been used as a water supply in an otherwise very dry area. Pumping of water has reduced the depth of the lake from 70m to 50m since 1921 (Skelton 1990a,1990b,1990c, Bruton 1995). The animals appear to congregate above an underwater shelf  where they presumably obtain food from the bat colonies above them. This shelf is in danger of being exposed by the reducing water level. It is probably safe to say that this is one of the most endangered fishes in the world. During a dive in the lake in Aigamas Cave divers reported seeing hundreds of individuals (Speleofilms, Le Souffle du Dragon, Gerald Favre, no date). A population survey in 2019 recorded a maximum of 119 individual fishes (Jacobs et al. 2019).

This species is found in Ecoregion 79 (Karstveld Sink Holes) of Thieme et al. (2005). This is an area of subterranean and spring systems which is regionally outstanding faunistically, with a conservation status of endangered and a priority class of 4 (Skelton 2005).

Museum Holdings

Trewavas (1936) records that there were 12 specimens in addition to the type series but the BMNH collection contains only ten specimens from that period: BMNH 1935.3.20:179‑188. Also BMNH 1971.8.10:1‑2, KMMA 74‑21‑P‑16‑17, ZSMH 6112 (Teugels 1986:134‑137). There are three specimens in the Department of Ichthyology, Rhodes University, South Africa (Jubb 1958). AMG/P 2679 (Skelton and Teugels 1991).

Key References

Note: Some marvellous film of this animal can be seen in the Speleofilm’s film: Le Souffle du Dragon (Speleofilms, Gerald Favre).

Trewavas, E. Journal Article 1936 Dr Karl Jordans expedition to South West Africa and Angola: the freshwater fishes
Jubb, R. A. Journal Article 1958 A cave-dwelling cat-fish Clarias cavernicola Trewavas 1936, in South-West Africa
Jubb, R. A. Book 1967 Freshwater fishes of Southern Africa
Bok, A. Thesis 1968 [The eyes, brain and sense organs of Clarias cavernicola]
Jubb, R. A. Journal Article 1969 Fishes of the dolomitic limestone caves and sinkholes of southern Africa
Hennig, H. Journal Article 1971 Note on the blind catfish Clarias cavernicola
Hennig, H. Journal Article 1977 Note on the blind catfish Clarias cavernicola
Miller, R. R. Book 1977 Red Data Book, Volume 4, Freshwater fishes
Scheide, P. Journal Article 1977 Cave-dwelling catfish
Von Wrede, P. Journal Article 1977 Zusammenfassung der Bericht nber den blinde hoehlenfisch Clarias cavernicola Trewavas 1936
Von Wrede, P. Journal Article 1977 Zur kenntnis der Nahrungsquelle des hoehlenfisches Clarias cavernicola Trewavas 1936
Teugels, G. G. Journal Article 1982 Preliminary data of a systematic outline of the African species of the the genus Clarias (Pisces, Clariidae)
Teugels, G.G. Journal Article 1982 A systematic outline of the African species of the the genus Clarias (Pisces, Clariidae) with an annotated bibliography
Teugels, G.G. Journal Article 1986 A systematic revision of the African species of the genus Clarias (Pisces, Clariidae)
Sefton, M., Martini, J. and Ellis, R. Journal Article 1986 Cave descriptions
Skelton, P. H. Journal Article 1987 Cave Catfish / Spelonk-barber
Maxwell, C. Journal Article 1988 Underwater in Dragons Breath Cave
Penney, A. J. Journal Article 1988 The aquatic fauna of Dragon's Breath lake
Penney, A. J. Journal Article 1988 Notes on the collection of blind cave catfish from Aigamas Cave during Swex '87
Skelton, P. H. Journal Article 1989 Gems of a different kind
Skelton, P. H. Journal Article 1990 The conservation and status of threatened fishes in southern Africa
Skelton, P. H. Journal Article 1990 The status of fishes from the sinkholes and caves in Namibia
Skelton, P. H. Journal Article 1990 The status of fishes from sinkholes and caves in Namibia
Irish, J Journal Article 1991 Conservation aspects of karst waters in Namibia
Skelton, P. H. and Teugels, G. G. Journal Article 1991 A review of the Clariid catfishes (Siluroidei, Clariidae) occuring in southern Africa
Irish, J Journal Article 1991 Cave investigations in Namibia. 1. biospeleology, ecology, and conservation of Dragon's Breath Cave
Bruton, M. Journal Article 1995 Threatened fishes of the world: Clarias cavernicola Trewavas,1936 (Clariidae)
Kensley, B. Journal Article 1995 A new genus of aquatic cave-dwelling isopod from Namibia (Crustacea: Isopoda: Asellota)
Marais, E. and Irish, J. Journal Article 1997 Cave investigations in Namibia, IV. Aikab hemicenote, and other karst phenomina in the Etosha national Park
Churchill, S., Draper, R. and Marais, E. Journal Article 1997 Cave utilisation by Namibian bats: population, microclimate and roost selection
Davis, B. and Day, J. Book 1998 Vanishing waters
Barnard, P. Book 1998 Biological diversity in Namibia
Curtis, B., Roberts, K.S., Griffin, M., Bethune, S., Hay, C.J. and Kolberg, H. Journal Article 1998 Species richness and conservation of Namibian freshwater macro-invertebrates, fish and amphibians
Diogo, R., Chardon, M. and Vandewalle, P. Journal Article 2003 On the osteology and myology of the cephalic region and pectoral girdle of Heteropneustes fossilis (Siluriformes: Heteropneustidae), with comments on the phylogenetic relationships between Heteropneustes and clariid fishes
Thieme, M.L., Abell, R., Stiassny, M.L.J.,Skelton, P., Lehner, B., Teugels, G., Dinerstein, E., Kamdem-Toham, A., Burgess, B., and Olson, D. Book 2005 Freshwater ecoregions of Africa and Madagascar. A conservation assessment
Scott, L. Book Section 2005 Ecoregion 79. Karstveld sinkholes
Agnese, J.F. and Teugels, G. Journal Article 2005 Insight into the phylogeny of African Clariidae (Teleostei, Siluriformes); Implications for their body shape evolution, biogeography, and taxonomy
Diogo, R. Book 2005 Morphological evolution, aptations, homoplasies, constraints and evolutionary trends. Catfishes as a case study on general phylogeny and macroevolution
Darwall, W.R.T., Smith, K.G., Tweddle, D. and Skelton, P. Book 2009 The status and distribution of freshwater biodiversity in southern Africa
Jacobs, F.J., Hay, C.H., Jacobs, P.G. and Næsje, T.F. Report 2019 A baseline study of the critically endangered cave-dwelling catfish (Clarias cavernicola)
Jacobs, F., Hay, C., Jacobs, G. and Næsje, T. Report 2019 Preliminary technical report: A baseline study of the critically endangered cave-dwelling catfish Clarias cavernicola. Report no. MFMR-PRFR1-2019-04-30