Electric fishes

An electric fish is a fish that can generate electric fields. It is said to be electrogenic; a fish that has the ability to detect electric fields is said to be electroreceptive. Most fish that are electrogenic are also electroreceptive. Electric fish species can be found both in the sea and in freshwater rivers of South America and Africa. Many fish such as sharks, rays and catfishes can detect electric fields, and are thus electroreceptive, but as they cannot generate an electric field they are not classified as electric fish. Most common bony fish (teleosts), including most fish kept in aquaria or caught for food, are neither electrogenic nor electroreceptive.

Strongly and weakly electric fish
Electric fish produce their electric fields from a specialized structure called an electric organ. This is made up of modified muscle or nerve cells, which became specialized for producing electric fields. Typically this organ is located in the tail of the electric fish. The electrical output of the organ is called the electric organ discharge (EOD).

Fish that have an EOD that is powerful enough to stun their prey are called strongly electric fish. The amplitude of the signal can range from 10 to 500 volts with a current of up to 1 ampere. Typical examples are the electric eel (Electrophorus electricus; not a true eel but a knifefish), the electric catfishes (family Malapteruridae), and electric rays (order Torpediniformes).

By contrast, weakly electric fish generate a discharge that is typically less than one volt in amplitude. These are too weak to stun prey, but are used for navigation, object detection (electrolocation) and communication with other electric fish (electrocommunication). Some of the best known and most studied examples are Peters' elephantnose fish (Gnathonemus petersi) and the black ghost knifefish (Apteronotus albifrons).

The EOD waveform takes two general forms depending on the species. In some species the waveform is continuous and almost sinusoidal (for example the genera Apteronotus, Eigenmannia and Gymnarchus) and these are said to have a wave-type EOD. In other species, the EOD waveform consists of brief pulses separated by longer gaps (for example Gnathonemus, Gymnotus, Raja) and these are said to have a pulse-type EOD.

Table of electric fish
This is a table of all known electric fish species within fresh water. In salt water there is only one order, the Torpediniformes (electric rays), inside the chondrichthyes that shows species generating even strong electric pulses (genus Torpedo spp., which counts 22 known species).

Boooks

 * Bullock, T.H., Heiligenberg, W. (eds) (1986) Electroreception. Wiley, 722 pp.
 * Heiligenberg, W. (1991) Neural nets in electric fish. MIT Press, 179 pp.
 * Moller, P. (1995) Electric Fishes: History and Behavior. Chapman & Hall, 583 pp.

Papers

 * Allee, S. J. (2007). Neuroendocrine control of a dynamic communication signal. Dissertation Abstracts International: Section B: The Sciences and Engineering.
 * Baier, B., & Kramer, B. (2007). Electric communication during courtship and spawning in two sibling species of dwarf stonebasher from southern Africa, Pollimyrus castelnaui and P. marianne (Mormyridae, Teleostei): Evidence for a non species-specific communication code? : Behaviour Vol 144(1) Jan 2007, 115-142.
 * Carlson, B. A. (2003). Single-Unit Activity Patterns in Nuclei That Control the Electromotor Command Nucleus during Spontaneous Electric Signal Production in the Mormyrid Brienomyrus brachyistius: Journal of Neuroscience Vol 23(31) Nov 2003, 10128-10136.
 * Carlson, B. A., & Hopkins, C. D. (2004). Stereotyped temporal patterns in electrical communication: Animal Behaviour Vol 68(4) Oct 2004, 867-878.
 * Carlson, B. A., & Kawasaki, M. (2006). Ambiguous Encoding of Stimuli by Primary Sensory Afferents Causes a Lack of Independence in the Perception of Multiple Stimulus Attributes: Journal of Neuroscience Vol 26(36) Sep 2006, 9173-9183.
 * Chacron, M. J. (2006). Nonlinear Information Processing in a Model Sensory System: Journal of Neurophysiology Vol 95(5) May 2006, 2933-2946.
 * Chacron, M. J., Maler, L., & Bastian, J. (2005). Feedback and Feedforward Control of Frequency Tuning to Naturalistic Stimuli: Journal of Neuroscience Vol 25(23) Jun 2005, 5521-5532.
 * Cowan, N. J., & Fortune, E. S. (2007). The critical role of locomotion mechanics in decoding sensory systems: Journal of Neuroscience Vol 27(5) Jan 2007, 1123-1128.
 * Curtis, C. C., & Stoddard, P. K. (2003). Mate preference in female electric fish, Brachyhypopomus pinnicaudatus: Animal Behaviour Vol 66(2) Aug 2003, 329-336.
 * Deng, T.-S., & Tseng, T.-C. (2000). Evidence of circadian rhythm of electric discharge in Eigenmannia virescens system: Chronobiology International Vol 17(1) 2000, 43-48.
 * Dewsbury, D. A. (1966). Diurnal fluctuations in the discharge frequency of a gymnotid electric fish: Psychonomic Science Vol 6(1) 1966, 35-36.
 * Doiron, B., Chacron, M. J., Maler, L., Longtin, A., & Bastian, J. (2003). Inhibitory feedback required for network oscillatory responses to communication but not prey stimuli: Nature Vol 421(6922) Jan 2003, 539-543.
 * Dunlap, K. D., Castellano, J. F., & Prendaj, E. (2006). Social interaction and cortisol treatment increase cell addition and radial glia fiber density in the diencephalic periventricular zone of adult electric fish, Apteronotus leptorhynchus: Hormones and Behavior Vol 50(1) Jun 2006, 10-17.
 * Dunlap, K. D., & Larkins-Ford, J. (2003). Production of aggressive electrocommunication signals to progressively realistic social stimuli in male Apteronotus leptorhynchus: Ethology Vol 109(3) Mar 2003, 243-258.
 * Dunlap, K. D., Smith, G. T., & Yekta, A. (2000). Temperature dependence of electrocommunication signals and their underlying neural rhythms in weakly electric fish, Apteronotus leptorhynchus: Brain, Behavior and Evolution Vol 55(3) Mar 2000, 152-162.
 * Dunlap, K. D., & Zakon, H. H. (1998). Behavioral actions of androgens and androgen receptor expression in the electrocommunication system of an electric fish, Eigenmannia virescens: Hormones and Behavior Vol 34(1) Aug 1998, 30-38.
 * Ellis, L. D., Mehaffey, W. H., Harvey-Girard, E., Turner, R. W., Maler, L., & Dunn, R. J. (2007). SK channels provide a novel mechanism for the control of frequency tuning in electrosensory neurons: Journal of Neuroscience Vol 27(35) Aug 2007, 9491-9502.
 * Engelmann, J., Bacelo, J., van den Burg, E., & Grant, K. (2006). Sensory and Motor Effects of Etomidate Anesthesia: Journal of Neurophysiology Vol 95(2) Feb 2006, 1231-1243.
 * Fortune, E. S. (2006). The decoding of electrosensory systems: Current Opinion in Neurobiology Vol 16(4) Aug 2006, 474-480.
 * Graff, C., Kaminski, G., Gresty, M., & Ohlman, T. (2004). Fish Perform Spatial Pattern Recognition and Abstraction by Exclusive Use of Active Electrolocation: Current Biology Vol 14(9) May 2004, 818-823.
 * Herfeld, S., & Moller, P. (1998). Effects of 17alpha -methyltestosterone on sexually dimorphic characters in the weakly discharging electric fish, Brienomyrus niger (Gunther, 1866)(Mormyridae): Electric organ discharge, ventral body wall indentation, and anal-fin ray bone expansion: Hormones and Behavior Vol 34(3) Dec 1998, 303-319.
 * Liu, H. (2007). Individual variation and hormonal modulation of sodium channel alpha and beta1 subunits in the electric organ correlate with variation in a social signal. Dissertation Abstracts International: Section B: The Sciences and Engineering.
 * Macadar, O., & Silva, A. (2007). Electric communication in South American gymnotiform fishes: Revista Latinoamericana de Psicologia Vol 39(1) 2007, 31-45.
 * Mandriota, F. J., Thompson, R. L., & Bennett, M. V. (1965). Classical conditioning of electric organ discharge rate in mormyrids: Science 150(3704) 1965, 1740-1742.
 * Marvit, P. (2000). Behavioral studies of acoustic sensitivity and discrimination in the sonic fish pollimyrus (mormyridae). Dissertation Abstracts International: Section B: The Sciences and Engineering.
 * Mehaffey, W. H., Doiron, B., Maler, L., & Turner, R. W. (2005). Deterministic Multiplicative Gain Control with Active Dendrites: Journal of Neuroscience Vol 25(43) Oct 2005, 9968-9977.
 * Paintner, S., & Kramer, B. (2003). Electrosensory basis for individual recognition in a weakly electric, mormyrid fish, Pollimyrus adspersus (Gunther, 1866): Behavioral Ecology and Sociobiology Vol 55(2) Dec 2003, 197-208.
 * Piccolino, M. (2007). The taming of the electric ray: From a wonderful and dreadful "art" to "animal electricity" and "electric battery": Whitaker, Harry (Ed); Smith, C U M (Ed); Finger, Stanley (Ed).
 * Rose, G. J. (2004). Insights into neural mechanisms and evolution of behaviour from electric fish: Nature Reviews Neuroscience Vol 5(12) Dec 2004, 943-951.
 * Sawtell, N. B., Williams, A., Roberts, P. D., von der Emde, G., & Bell, C. C. (2006). Effects of Sensing Behavior on a Latency Code: Journal of Neuroscience Vol 26(32) Aug 2006, 8221-8234.
 * Silva, A., Perrone, R., & Macadar, O. (2007). Environmental, seasonal, and social modulations of basal activity in a weakly electric fish: Physiology & Behavior Vol 90(2-3) Feb 2007, 525-536.
 * Smith, G. T., Allen, A. R., Oestreich, J., & Gammie, S. C. (2005). L-Citrulline Immunoreactivity Reveals Nitric Oxide Production in the Electromotor and Electrosensory Systems of the Weakly Electric Fish, Apteronotus leptorhynchus: Brain, Behavior and Evolution Vol 65(1) Jan 2005, 1-13.
 * Stoddard, P. K., Markham, M. R., Salazar, V. L., & Allee, S. (2007). Circadian rhythms in electric waveform structure and rate in the electric fish Brachyhypopomus pinnicaudatus: Physiology & Behavior Vol 90(1) Jan 2007, 11-20.
 * Szalisznyo, K., Longtin, A., & Maler, L. (2006). Altered sensory filtering and coding properties by synaptic dynamics in the electric sense: Neurocomputing: An International Journal Vol 69(10-12) Jun 2006, 1070-1075.
 * Tallarovic, S. K., & Zakon, H. H. (2005). Electric organ discharge frequency jamming during social interactions in brown ghost knifefish, Apteronotus leptorhynchus: Animal Behaviour Vol 70(6) Dec 2005, 1335-1365.
 * Tan, E. W., Nizar, J. M., Carrera-G, E., & Fortune, E. S. (2005). Electrosensory interference in naturally occurring aggregates of a species of weakly electric fish, Eigenmannia virescens: Behavioural Brain Research Vol 164(1) Oct 2005, 83-92.
 * Terleph, T. A. (2003). The effects of social interaction on behavior and electric organ discharge in two species of mormyrid fish: Gnathonemus petersii (gunther, 1862) and brienomyrus niger (gunther, 1866), mormyridae, teleostei. Dissertation Abstracts International: Section B: The Sciences and Engineering.
 * Van Wettering, J. R. (1996). Discrimination of electric signals: Implications for electrocommunication in the African electric catfish malapterurus electricus. Dissertation Abstracts International: Section B: The Sciences and Engineering.
 * Voustianiouk, A. (2003). A weakly discharging electric fish, Gnathonemus petersii (mormyridae, teleostei), as a model of integrated androgen effects on structure and behavior. Dissertation Abstracts International: Section B: The Sciences and Engineering.
 * Walton, A. G. (2006). Maze learning and recall in weakly electric fish, mormyrus rume proboscirostris boulenger 1898 (teleostei, Mormyridae): Sensory bases. Dissertation Abstracts International: Section B: The Sciences and Engineering.
 * Zakon, H. H. (2003). Insight into the mechanisms of neuronal processing from electric fish: Current Opinion in Neurobiology Vol 13(6) Dec 2003, 744-750.
 * Zakon, H. H. (2006). Divide and conquer: Cell addition and aggressive signaling in electric fish: Hormones and Behavior Vol 50(1) Jun 2006, 8-9.