From Wikipedia, the free encyclopedia
Jump to: navigation, search
Banded knifefishes
Gymnotus inaequilabiatus.jpg
Gymnotus inaequilabiatus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Gymnotiformes
Family: Gymnotidae
Genus: Gymnotus
Linnaeus, 1758

Gymnotus is a genus of fish in the order Gymnotiformes found widely in the Neotropics, including the Amazon. Some Gymnotus species live in the leaf litter and root tangles of river banks. Other species are specialized to live on floodplains within the rootmats of floating meadows. Several species are broadly adapted to live in both of these habitats. Gymnotus are nocturnal predators feeding on insects, crustaceans, and other fish. They generate weak electric fields used in locating objects, and also for communication in which the males court females using stereotyped electrical "songs".[citation needed]

Small scales are always present on this fish. The mouth is superior, meaning it is turned upwards. The anal fin terminates at a point near the tip of the tail. Species of Gymnotus reach up to about 100 cm in length. This is the most widespread genus of the order Gymnotiformes, extending from southern Mexico to Argentina. They also occur in Trinidad.[1]

Michael Faraday extensively tested the electrical properties of a Gymnotus specimen, imported from Suriname. For a span of four months, Faraday carefully and humanely measured the electrical impulses produced by the animal by pressing shaped copper paddles and saddles against the specimen. Through this method, Faraday determined and quantified the direction and magnitude of electric current, and proved the animal's impulses were in fact electrical by observing sparks and deflections on a galvanometer.[2]


There are currently 39 recognized species in this genus:


  1. ^ Nelson, J.S. (2006). Fishes of the World. John Wiley & Sons, Inc. ISBN 0-471-25031-7. 
  2. ^ Fifteenth Series, Experimental Researches in Electricity. Philosophical Transactions of the Royal Society. 1838.
  3. ^ Milhomem, S.S.R., Crampton, W.G.R., Pieczarka, J.C., Shetka, G.H., Silva, D.S. & Nagamachi, C.Y. (2012): Gymnotus capanema, a new species of electric knife fish (Gymnotiformes, Gymnotidae) from eastern Amazonia, with comments on an unusual karyotype. Journal of Fish Biology, 80 (4): 802–815.
  4. ^ Rangel-Pereira, F.S. (2014): Gymnotus capitimaculatus, a new species of electric fish from rio Jucuruçu basin, northeastern Brazil (Ostariophysi: Gymnotiformes: Gymnotidae). Vertebrate Zoology, 64 (2): 169–175.
  5. ^ Cognato, D.P., Richer-de-Forges, M.M., Albert, J.S. & Crampton, W.G.R. "Gymnotus chimarrao, a new species of electric fish (Gymnotiformes: Gymnotidae) from Southern Brazil.". Ichthyologial Explorations of Freshwaters, 18 (4): 375–382. 
  6. ^ Maxime, E.L. & Albert, J.S. (2014): Redescription of the Tuvirão, Gymnotus inaequilabiatus Valenciennes, 1839, Using High-Resolution X-ray Computed Tomography. Copeia, 2014 (3): 462–472.
  7. ^ Rangel-Pereira, F.d.S. (2012): Gymnotus interruptus, a new species of electric fish from the Rio de Contas basin, Bahia, Brazil (Teleostei: Gymnotiformes: Gymnotidae). Vertebrate Zoology, 62 (3): 363–370.