Gnathonemus petersii (Günther, 1862)
Size:
Maximum size: 350 mm SL.
Habitat:
small to large rivers
Gnathonemus petersii (Günther 1862)
EOL Text
Sporozoa-infections, other. Parasitic infestations (protozoa, worms, etc.)
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| Rights holder/Author | Allan Palacio, FishBase |
| Source | http://www.fishbase.org/Diseases/diseasesList.cfm?ID=2085&StockCode=2280 |
Importance:
fisheries: subsistence fisheries; aquarium: commercial
| License | http://creativecommons.org/licenses/by-nc/3.0/ |
| Rights holder/Author | Susan M. Luna, FishBase |
| Source | http://www.fishbase.org/summary/SpeciesSummary.php?id=2085 |
Biology:
Occurs close to the bottom where it probes for food with the long snout. Territorial and usually aggressive towards members of its own species. This behavior has been shown to involve electric organ discharge (EOD) activity (Ref. 10011). Feeds mostly at night on worms and insects (Ref. 7020), probably aided by electro-sensory inputs (Ref. 10011). Electroreceptors are distributed over the entire head, the dorsal and ventral regions of the body, but absent from the side and the caudal peduncle where the electric organ is located (Ref. 10011). Sex-related EOD characteristics in this species has been demonstrated in the laboratory with freshly imported samples during the breeding season; such EOD dimorphism changed with time in captivity (Ref. 10764; 10766). Lead nitrate in water significantly increased EOD rate and selectively altered the EOD waveform of this species (Ref. 10469). Dubbed a `hearing specialist' having auditory abilities in the range of 100-2500 Hz, with `best frequencies' between 300 and 600 Hz (Ref. 10830). Aquarium keeping: in groups of 5 or more individuals; minimum aquarium size 150 cm; not recommended for home aquariums (Ref. 51539).
| License | http://creativecommons.org/licenses/by-nc/3.0/ |
| Rights holder/Author | Susan M. Luna, FishBase |
| Source | http://www.fishbase.org/summary/SpeciesSummary.php?id=2085 |
Sporozoa-infection (Myxobolus sp.). Parasitic infestations (protozoa, worms, etc.)
| License | http://creativecommons.org/licenses/by-nc/3.0/ |
| Rights holder/Author | Allan Palacio, FishBase |
| Source | http://www.fishbase.org/Diseases/diseasesList.cfm?ID=2085&StockCode=2280 |
Peters' elephantnose fish:
Peters' elephant-nose fish (Gnathonemus petersii; syn. Gnathonemus brevicaudatus Pellegrin, 1919, Mormyrus petersii Günther, 1862[2]) is an African freshwater elephantfish in the genus Gnathonemus. Other names in English include elephantnose fish, long-nosed elephant fish, and Ubangi mormyrid, after the Ubangi River. As the Latin name petersii confirms it is named after someone called "Peters" (probably Wilhelm Peters), although the apostrophe is often misplaced and the common name given as "Peter's elephantnose fish". It uses electrolocation to find prey, and has the largest brain-to-body weight ratio of all known vertebrates.[1]
Description[edit]
Peters' elephantnose fish are native to the rivers of West and Central Africa, in particular the lower Niger River basin, the Ogun River basin and in the upper Chari River. It prefers muddy, slowly moving rivers and pools with cover such as submerged branches. It is a dark brown to black in colour, laterally compressed (averaging 23–25 cm), with a rear dorsal fin and anal fin of the same length. Its caudal or tail fin is forked. It has two stripes on its lower pendicular. Its most striking feature, as its names suggest, is a trunk-like protrusion on the head. This is not actually a nose, but a sensitive extension of the mouth, that it uses for self-defense, communication, navigation, and finding worms and insects to eat. This organ is covered in electroreceptors, as is much of the rest of its body. The elephantnose fish has poor eyesight and uses a weak electric field, which it generates with specialized cells called electrocytes, which evolved from muscle cells, to find food, to navigate in dark or turbid waters, and to find a mate. Peters' elephantnose fish live to about 6-10 years, but there are reports of them living even longer.
In the aquarium[edit]
 |
This article is written like a manual or guidebook. (November 2014) |
Peters' elephantnose fish is probably the most commonly available Mormyrid in aquarium stores in the USA. In the aquarium (which should be at least 200 liters) it is timid, preferring a heavily planted environment with subdued lighting. Ideally, a pipe or hollow log should be provided. The substrate should ideally be soft sand to allow the fish to sift through it with its delicate extended lip. It feeds on small worms (bloodworms) and aquatic invertebrates such as mosquito larvae, but in the aquarium will usually accept frozen or even flake food. How peaceful an elephantnose fish is can depend on the individual; some are quite aggressive with other species, while others are retiring. They may be kept in a community aquarium with peaceful species who share their water preferences. However, unless kept in an aquarium of over 400 liters, it is unwise to keep more than one elephantnose fish as they can be territorial. The conditions suggested to keep them in an aquarium are as follows: pH of 6.8 to 7.2, water temperature 26 to 28 degrees Celsius, and water of medium hardness. The substrate should always be something that does not irritate the sensitive snout of the fish.
The weak electrical impulses generated by this fish can be made audible by placing two electrodes in the fish tank that are then hooked up to an audio amplifier or a piezoelectric earbud. The elephant nose fish can use its electosensing to detect moving prey and worms in the substrate.
Although the elephant nose fish was once thought to have poor eyesight, it is now known to have good low light vision. Its eyes use a combination of photonic crystals, parabolic mirrors and a clustered arrangement of rods and cones. [3]
See also[edit]
Notes[edit]
- ^ a b Nilsson G (1996) "Brain and body oxygen requirements of Gnathonemus petersii, a fish with an exceptionally large brain" Journal of Experimental Biology, 199(3): 603-607. Download
- ^ "Gnathonemus petersii". Integrated Taxonomic Information System. Retrieved July 3, 2007.
- ^ http://www.sciencemag.org/content/suppl/2012/06/27/336.6089.1730-b.DC1/SciencePodcast_120629.pdf
References[edit]
- Froese, Rainer and Pauly, Daniel, eds. (2006). "Gnathonemus petersii" in FishBase. May 2006 version.
| License | http://creativecommons.org/licenses/by-sa/3.0/ |
| Rights holder/Author | Wikipedia |
| Source | http://en.wikipedia.org/w/index.php?title=Peters'_elephantnose_fish&oldid=654998565 |
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."
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| Rights holder/Author | Sullivan, John P., Sullivan, John P., Hopkins, Carl D., Africhthy |
| Source | http://mormyrids.lifedesks.org/pages/2063 |
Sporozoa Infection (Hennegya sp.). Parasitic infestations (protozoa, worms, etc.)
| License | http://creativecommons.org/licenses/by-nc/3.0/ |
| Rights holder/Author | Allan Palacio, FishBase |
| Source | http://www.fishbase.org/Diseases/diseasesList.cfm?ID=2085&StockCode=2280 |
Range Description:
This species is known from Nigeria to Central African Republic, and south to Angola and Zambia
Central Africa: Gnathonemus petersii is known from throughout the Congo River basin. In the Lower Guinea region, it is known from the Cross Mungo, Wouri, Lokoundjé, and Lower Sanaga Rivers.
Western Africa: It is found in the Lower Niger, Ogun, Cross basin and This species is known from upper Chari basin.
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| Rights holder/Author | © International Union for Conservation of Nature and Natural Resources |
| Source | http://www.iucnredlist.org/apps/redlist/details/181553 |
Nematode Infection (general). Parasitic infestations (protozoa, worms, etc.)
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| Rights holder/Author | Allan Palacio, FishBase |
| Source | http://www.fishbase.org/Diseases/diseasesList.cfm?ID=2085&StockCode=2280 |
Africa: Niger to Congo River basins (Ref. 3203).
| License | http://creativecommons.org/licenses/by-nc/3.0/ |
| Rights holder/Author | Susan M. Luna, FishBase |
| Source | http://www.fishbase.org/summary/SpeciesSummary.php?id=2085 |