Rhamdia urichi

(Norman 1926) Mees 1974

Rhamdia urichi
Redrawn by Rhian Kendall from Norman (1926)


Caecorhamdia urichi  Norman 1926

Caecorhamdella urichi  (Norman 1926) Hubbs 1938 lapsus calami

Rhamdia quelen urichi  (Norman 1926) Mees 1974

Hubbs (1938:264) used the generic name Caecorhamdella for this species but this was obviously a mistake since the correct name is used three pages later. The generic name was misspelt Caecohamdia by Wolf (1934, 1938).


Trinidad and Tobago


The description was based on a syntype series of two individuals: BMNH 1926.7.28:1‑2. This species is the type species by monotypy of the genus Caecorhamdia.


Known only from the type locality: Guacharo Cave (or Oropuche, Oropouche, or Cumaca Cave) Trinidad (10o30’N, 61o30’W).


Guacharo Cave is a vadose cave with a stream running through it. The fishes tend to be concentrated in the resurgent sump at the end of the cave. It is thought that the main body of the population is concentrated in the groundwater supplying the cave and nothing is known of this habitat (Darlington 1995). It is highly likely that the large population of Oilbirds (Steatornis caripensis) provided much of the food supply for the aquatic biota. Whether the fishes feed directly on bird products (faeces, dead bodies), or consume invertebrates that do, is not known. Rutherford (2019) counted a population of 1400 individuals in the cave. This is a very significant increase on the 200 reported by Snow (1962). Holland et al (2009) describe the ecology and habits of this bird.


Norman (1926) erected the genus Caecorhamdia "in order to draw attention to this interesting fish". He realised however "that this procedure is somewhat unsatisfactory, for, were the eyes developed, the [fishes] would be probably be identified with the species Rhamdia queleni [sic]". Mees (1974:160-165) examined one preserved specimen and living animals at the type locality. His observations indicated that neither generic nor specific distinctions were merited. Instead of synonymising the cave form completely with R. quelen he gave it subspecific status. In common with the cave form of Poecilia mexicana there is a suggestion that a fully evolved troglomorphic fish is undergoing intogression with an epigean form. At Guacharo Cave it is possible to observe all degrees of pigmentation and eye morphology, from pure quelen at the entrance to pure urichi at the end of the cave (observations made by Jack Price; John Endler pers. comm.; Romero 1983:82). Silfvergrip (1996) does not recognise the subspecies. If a troglomorphic, and stygobitic, fish is resident in the area of this cave it will require a separate status and name. Rhamdia urichi seems sensible. However, recent studies by Romero and co-workers (Romero and Creswell 2000, Romero and Creswell 2000, Romero et al. 2002) suggests that the troglomorphic form may have been replaced by an epigean morph. It still remains possible that the troglomorphic form exists in more remote passages, none of which have ever been entered.

Phillip et al. (2013) comment: "A troglomorphic form of Rhamdia cf. quelen had been misidentified as a separate species, Caecorhamdia urichi Norman (1926), and is now considered a synonym of R. cf. quelen.

Biological Notes

Kenny (1995) provides the following very useful observations. They strongly support a view that there was never a highly evolved subterranean fish in the cave and that the syntypes (BMNH 1926.7.28:1‑2) were at the unpigmenred and small-eyed end of the spectrum of variability. (Text courtesy of Amy Deacon).

Caecorhamdía urichi

Given the extreme variability of eye development, pigmentation and barbel length in the blind catfish of the Oropouche Cave, l am inclined to the view that Caecorhamdia urichi was conspecific with Rhamdia quelen. Mees (1974) suggests subspecific status for the blind catfish of the Oropouche Cave. l question this. l have maintained in captivity several specimens and not only the degree of eye formation is variable, but barbel length and colour. Some are pigment free and short barbelled, others range through grey to a very dark grey with longer barbels, and some are even spotted. Moreover, there is no doubt that the pigment-free forms do in fact develop pigmentation in prolonged exposure to illumination. Mees actually visited the Oropouche Cave with Jack Price and Victor Quesnel and spent some time trying to collect specimens. He collected two. Perhaps his methods may not have been up to it. Had he employed a mask and snorkel and chumming he might have seen the very wide variation which l have seen, and had he used a small seine he would certainly have collected more.

Conservation Status


Museum Holdings

As above plus: BMNH 1926.7.28:3, RMNH 26733 (Mees 1974).

Internet Resources

Amy Deacon's observations on this fish

Key References

Norman, J. R. Journal Article 1926 A new blind catfish from Trinidad, with a list of blind cave-fishes
Boeseman, M. Journal Article 1960 The freshwater fishes of the islands of Trinidad
Snow, D.W. Journal Article 1961 The natural history of the Oilbird, Steatornis caripensis, in Trinidad, W.I. Part 1. General behaviour and breeding habits.
Snow, D.W. Journal Article 1962 The natural history of the Oilbird, Steatornis caripensis, in Trinidad, W.I. Part 2. Population, breeding ecology and food
Mees, G.F. Journal Article 1974 The Auchenipteridae and Pimelodidae of Surinam (Pisces, Nematognathi)
Quesnel, V. Journal Article 1976 Report on the trip to the Oropouche Cave on 7th March
Romero, A. Journal Article 1983 Introgressive hybridisation in the Astyanax fasciatus (Pisces, Characidae) population at La Cueva Chica
Quesnel, V. Journal Article 1985 Field Trip to the Cumaca Cave. 1985-3: 2.
Langecker, T.G. and Wilkens, H. Journal Article 1992 Comparative ultrastructural studies on the pineal organ of the Mexican catfish Rhamdia laticauda Heckel, 1858 and one of its cave-dwelling derivatives (Pimelodidae, Teleostei)
Junge, P. Journal Article 1992 Egg size and larval development of epigean and cave forms of Rhamdia guatemalensis (Pimelodidae, Pisces)
Shaw, T.R. Journal Article 1993 The history of cave studies in Trinidad, Jamaica, The Bahamas, and some other Caribbean islands
Darlington, J.P.E.C. Journal Article 1995 A review of current knowledge about the Oropouche or Cumaca Cave, Trinidad, West Indies
Kenny, J.S. Book 1995 Views from the bridge. A memoir of the freshwater fishes of Trinidad
Silfvergrip, A.M.C. Book 1996 A systematic revision of the neotropical catfish genus Rhamdia (Teleostei, Pimelodidae)
Romero, A. and Creswell, J. Conference Proceedings 2000 Eyes wide open: the "eyeless cave fish of Trinidad, W.I. is not blind
Carvalho Gomes, L. de, Golombieski, J.I., Chippari Gomes, A.R. and Baldisserotto, R. Journal Article 2000 Biology of Rhamdia quelen (Teleostei, Pimelodidae)
Romero, A. and Creswell, J. Journal Article 2000 In search of the elusive "eyeless" cave fish of Trinidad, W.I.
Romero, A., Singh, A., McKie, A., Manna, M., Baker, R. and Paulson, K.M. Journal Article 2001 Return to the Cumaca Cave, Trinidad, W.I.
Perdices, A., Bermingham, E., Montilla, A. and Doadrio, I. Journal Article 2002 Evolutionary history of the genus Rhamdia (Teleostei: Pimelodidae) in Central America
Romero, A., Singh, A., McKie, A., Manna, M., Baker, R., Paulson, K.M. and Creswell, J.E. Journal Article 2002 Replacement of the troglomorphic population of Rhamdia quelen (Pisces: Pimelodidae) by an epigean population of the same species in the Cumaca Cave, Trinidad, West Indies
Weber, A Thesis 2003 Taxonomie und Artstatus hohlenbewohnender und oberirdischer Welse der Gattung Rhamdia (Pimelodidae, Teleostei) in Mexiko
Shaw, P. Book 2009 A Register of the Caves of Trinidad and Tobago
Holland, R.A., Wikelski, M., Kummeth, F., and Bosque, C. Journal Article 2009 The secret life of Oilbirds: New insights into the movement ecology of a unique avian frugivore.
White, S. Journal Article 2012 Cumaca Cave Field Trip Report.2012-1
Phillip, D.A.T., Taphorn, D.C., Holm, E., Gilliam, J.F., Lamphere, B.A. and López-Fernández, H. Journal Article 2013 Annotated list and key to the stream fishes of Trinidad and Tobago
Deacon, A. Web Page 2015 The catfish of Cumaca Cave
Angrizani, R.C. and Malabarba, L.R. Journal Article 2018 Morphology and molecular data reveal the presence of two new species under Rhamdia quelen (Quoy & Gaimard, 1824) (Siluriformes: Heptapteridae) species complex
Scaglione, M.C., Cerutti, R.D., Arfuso, F. and Piccione, G. Journal Article 2018 Light and dark rations and the photic entrainment of circadian locomotor activity patterns in the South American Silver Catfish (Rhamdia quelen, Quoy & Gaimard, 1824)
Ricci, J.M.B.,Martinez, E.R.M., Butzge, A.J., Doretto, L.B., Oliveira, M.A., Bombardelli, R.A., Bogerd, J. and Nóbrega, R.H. Journal Article 2018 Characterization of vasa homolog in a neotropical catfish, Jundiá (Rhamdia quelen): Molecular cloning and expression analysis during embryonic and larval development
Koerber, S. and Reis, R.E. Journal Article 2019 The current situation of Rhamdia Bleeker, 1858 (Siluriformes: Heptapteridae) – Gather available information, define a zero point, and start all over again
Rutherford, M.G. Journal Article 2019 An update on the population of the Oilbird, Steatornis caripensis, in Trinidad, W.I.
Koerber, S. and Reis, R.E. Journal Article 2020 Evidence for the true type-locality of Rhamdia quelen (Siluriformes: Heptapteridae), and the geographical origin and invalid neotype designation of four of its synonyms
Warren, M.L. and Burr, B.M. Book 2020 Freshwater fishes of North America. Volume 2 Characidae to Poeciliidae
Thomas, M.R. and Sabaj, M.H. Book Section 2020 Heptapteridae: Seven-finned catfishes