Gnathonemus petersii

Gnathonemus petersii (Günther, 1862)

Original Published Description:

Günther, A. C. L. G. (1862).  Eine neue art von Mormyrus. Archiv für Naturgeschichte. 28, 64.

Common Names

Elephantnose fish, Peter's elephantnose, Ubangi mormyrid

Languages: English


General Description

Body is moderately deep, about 25-28% SL, with the greatest depth slightly anterior to the origin of the anal fin. The length of the head 20-25% SL, its depth, 66-75% of its length. Dorsal profile convex, descending in a straight line toward the head. Snout, 40% HL. Lower jaw with a cylindrical to tapering dermal appendix which is as long or longer than the snout; teeth small, notched, 3-5 in upper 5-6 in lower. Mouth small and terminal. Nostrils close together, about one eye diameter anterior to forward margin of eye. Eye, small, its diameter about 12% of length of head. Dorsal fin base length about 20-21% SL, with 27-29 rays. Dorsal fin originates above the 10th anal ray. Anal fin base about 27-28 % SL with 34-36 rays. Predorsal distance about 62 % SL; pre-anal distance about 56% SL. Caudal peduncle length about 3.3 times its depth, about 17% SL. 8 circumpeduncular scales. Scales along the lateral line, 63-70. Caudal fin covered with scales, deeply forked. Coloration: black brown with two distinct bands in the shape of parentheses “()” running from origin of dorsal to the origin of the anal fins. The light color of these bands fades in larger specimens. 

This is the best-known species of mormyrid due to its popularity in the international aquarium fish trade where it is known as the "elephantnose fish."


Electric Organ Discharge

In the laboratory,  EODs of G. petersii are often sexually dimorphic, with the male EOD longer in duration than that of the female. The EOD has three phases: an initial head negative phase which is visible only after amplifying the vertical axis of the display, followed by a head-positive then head-negative phase. The duration of the EOD is approximately 300 to 500 µs.  The presence of an initial head-negative phase to the waveform is characteristic of an electric organ with electrocytes which have penetrating stalks.

Author(s): Hopkins, Carl D.
Rights holder(s): Hopkins, Carl D.


Maximum size: 350 mm SL.

Author(s): Sullivan, John P.
Rights holder(s): Sullivan, John P.

Ecology and Distribution


Among the most widespread mormyrid species.  Such a large distribution suggests revisionary work may uncover multiple species. In Lower Guinea found in the Cross, Mungo, Wouri, Lokoundjé, and Lower Sanaga Rivers. Elsewhere widely distributed throughout central Africa from the Niger Delta to the Congo River basin. The holotype is from Old Calabar, at the mouth of the Calabar and Cross Rivers.  See FishBase for museum records and localities.


small to large rivers

Author(s): Sullivan, John P.
Rights holder(s): Sullivan, John P.


  • Gnathonemus brevicaudatus Pellegrin, 1919 (synonym (subjective = heterotypic))
  • Mormyrus petersii Günther, 1862 (synonym)
  • Gnathonemus histrio Fowler, 1936 (synonym (subjective = heterotypic))

Taxonomic Notes

Holotype (unique): BMNH 1863.9.29.14


[Anonymous] (Submitted).  .
Bigorne, R. (1990).  Mise en synonymie de Gnathonemus brevicaudatus Pellegrin, 1919 avec Gnathonemus petersii Gunther, 1862 (Teleostei, Mormyridae). Cybium. 14, 125-129.
Bigorne, R. (1990).  Mormyridae. (LévêqueC., PaugyD., TeugelsG G., Ed.).Faune des poissons d'eaux douces et saumâtres de l'Afrique de l'Ouest = The fresh and brackish water fishes of West Africa. 122-184. Paris, Tervuren (Belgium): ORSTOM, MRAC.
Bigorne, R. (2003).  Mormyridae. Faune des poissons d'eaux douces et saumâtres de l'Afrique de l'Ouest. 1, 154-222.
Blache, J. (1964).  Les poissons du bassin du Tchad et du bassin adjacent du Mayo Kebbi étude systématique et biologique. 1–483. Paris: ORSTOM.
Boulenger, G. A. (1899).  A revision of the genera and species of fishes of the family Mormyridae. Proceedings of the General Meetings for Scientific Business of the Zoological Society of London. 1898, 775-821.
Boulenger, G. A. (1909).  Catalogue of the Fresh-Water Fishes of Africa in the British Museum (Natural History). I, 373. London: British Museum (Natural History).
David, L., & Poll M. (1937).  Contribution à la faune ichthyologique du Congo Belge: Collections du Dr. H. Schouteden (1924-1926) et d'autres récolteurs. Annales du Musée du Congo Belge (Série 1). 3 (fasc. 5), 189–294.
Fowler, H. W. (1936).  Zoological results of the George Vanderbilt African Expedition of 1934. Part III,--The fresh water fishes. Proceedings of the Academy of Natural Sciences of Philadelphia. 88, 243–335. Abstract
Günther, A. C. L. G. (1862).  Eine neue art von Mormyrus. Archiv für Naturgeschichte. 28, 64.
Harder, W. (2000).  The Mormyridae and other Osteoglossomorpha (CD-ROM). World Biodiversity Database, CD-ROM Series. 2000, New York: Springer Verlag, ETI-UNESCO.
Hopkins, C. D., Lavoué S., & Sullivan J. P. (2007).  12. Mormyridae. (StiassnyM L J., TeugelsG G., HopkinsC D., Ed.).The Fresh and Brackish Water Fishes of Lower Guinea, West-Central Africa. 1, 220–334.
Pellegrin, J. (1919).  Poissons du Gribingui recueillis par M. Baudon. Description de sept espèces nouvelles. Bulletin de la Société Zoologique de France. 44,
Poll, M. (1939).  Les Poissons du Stanley-Pool. Annales du Musée du Congo belge. C.–Zoologie Série I.. 4, 1-60.
Poll, M. (1967).  Contribution à la Faune Ichthyologique de l'Angola. Publicações Culturais. 381. Lisbon: Companhia de Diamantes de Angola.
Vinciguerra, D. (1928).  Pesci raccolti dal March. Saverio Patrizi nel bacino del Congo. Annali del Museo Civico di Storia Naturale `Giacomo Doria'. 53, 1–28.
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