Electric catfish

Electric catfish
Malapterurus electricus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Siluriformes
Family:	Malapteruridae Bleeker, 1858
Genera
Malapterurus Paradoxoglanis

Electric catfish is the common name for the catfish (order Siluriformes) family Malapteruridae. This family includes two genera, Malapterurus and Paradoxoglanis with 19 species.^[1] Several species of this family have the ability to produce an electric shock of up to 350 volts using electroplaques of an electric organ.^[2] Electric catfish are found in tropical Africa and the Nile River.^[3] Electric catfish are usually nocturnal and feed primarily on other fish, incapacitating their prey with electric discharges.^[2]

Description

Malapteruridae is the only group of catfish with a well-developed electrogenic organ; however, electroreceptive systems are widespread in catfishes.^[4] The electrogenic organ is derived from anterior body musculature and lines the body cavity.^[3] Electric catfish do not have dorsal fins or fin spines. They have three pairs of barbels (the nasal pair is absent).^[3] The swim bladder with elongate posterior chambers, two chambers in Malapterrus and three in Paradoxoglanis.^[3]

It is one of the few electric species that have been conditioned by means of reward to discharge on signal. As reported in the New York Times, April 2, 1967, a researcher, Dr. Frank J. Mandriota of City College, NY, conditioned a M. Electricus to discharge on a light signal for a reward of live worms delivered automatically. This is a first in conditioning that modified neither glandular nor muscular responses.

They can grow as large as 100 centimetres (39 in) SL and about 20 kilograms (44 lb) in weight.^[3][2] All Paradoxoglanis species are much smaller.^[3] Most malapterurids are dwarf species less than 30 cm (12 inches) long.

Relationship to humans

The Nile fish was well known to the ancient Egyptians. Stories say that the Egyptians used this type of catfish when treating some nervous diseases. They would use only smaller fish, as a large fish may generate an electric shock of up to 300 or 400 volts. The Egyptians have depicted the fish in their mural paintings and elsewhere; the first known depiction of an electric catfish is on the slate palette of the pre-dynastic Egyptian ruler Narmer, about 3100 BC.^[4] An account of its electric properties was given by an Arab physician of the 12th century; then as now the fish was known by the suggestive name of Raad, abo el ra3ash,el ra3ad or Raash, which means thunder (literally trembler, shaker).

Though the shock an electric catfish can generate is not known to be fatal to humans,^[2] the catfish does use its electricity as a weapon to ward off predators.

References

 This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press. 

1. ^ Ferraris, Carl J., Jr. (2007). "Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types" (PDF). Zootaxa 1418: 1–628. http://silurus.acnatsci.org/ACSI/library/biblios/2007_Ferraris_Catfish_Checklist.pdf. Retrieved 2009-06-24. 
2. ^ ^{a b c d} Ng, Heok Hee (2000). "Malapterurus electricus". Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Malapterurus_electricus.html. Retrieved 2007-07-28. 
3. ^ ^{a b c d e f} Nelson, Joseph S. (2006). Fishes of the World. John Wiley & Sons, Inc. ISBN 0-471-25031-7. 
4. ^ ^{a b} Howes, George J. (1985). "The phylogenetic relationships of the electric catfish family Malapteruridae (Teleostei: Siluroidei)". Journal of Natural History 19: 37–67. doi:10.1080/00222938500770031.