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Gymnarchus niloticus Cuvier, 1829

Aba
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Gymnarchus niloticus
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Mauritania country information

Common names: [No common name]
Occurrence: native
Salinity: freshwater
Abundance: | Ref:
Importance: commercial | Ref: Mohamed Fall, K.O., 2005
Aquaculture: | Ref:
Regulations: | Ref:
Uses: no uses
Comments:
National Checklist:
Country Information: https://www.cia.gov/library/publications/resources/the-world-factbook/geos/mr.html
National Fisheries Authority:
Occurrences: Occurrences Point map
Main Ref: Mohamed Fall, K.O., 2005
National Database:

Common names from other countries

Classification / Names Populärnamn | synonymer | Catalog of Fishes(Släkte, Arter) | ITIS | CoL | WoRMS | Cloffa

> Osteoglossiformes (Bony tongues) > Gymnarchidae (Abas)
Etymology: Gymnarchus: Greek, gymnos = naked + Greek, archos = anus (Ref. 45335).
  More on author: Cuvier.

Environment: milieu / climate zone / depth range / distribution range Ekologi

; sötvatten bottenlevande; pH range: 6.5 - 8.0; dH range: 10 - 25; flodvandrande (Ref. 51243).   Tropical; 23°C - 28°C (Ref. 13614); 18°N - 2°N, 16°W - 36°E

Utbredning Länder | FAO områden | Ekosystem | Förekomster | Point map | Utplanteringar | Faunafri

Africa: basins of the rivers Senegal, Gambia, Volta, Niger and Chad in West Africa (Ref. 3530, 81275). Also in the Nile River basin (Ref. 3530, 28714) and Lake Turkana (Ref. 3530, 52331).

Size / Vikt / Age

Maturity: Lm ?  range ? - ? cm
Max length : 167 cm SL hane/ej könsbestämd; (Ref. 2915); publicerad maxvikt: 18.5 kg (Ref. 2915)

Short description Bestämningsnycklar | Morfologi | Morfometri

Taggstrålar i ryggfenan (totalt) : 0; Mjukstrålar i ryggfenan (totalt) : 183 - 230. Diagnosis: body very elongate (Ref. 28714, 81275), anguilliform (Ref. 81275), its depth 7.2-10.6 times in SL, and covered with tiny scales (Ref. 2915, 81275). Lateral line complete (Ref. 81275). Dorsal fin soft-rayed, extending almost over the entire length of back (Ref. 81275), stopping short of a naked tail (Ref. 28714). Pelvic, anal and caudal fins absent (Ref. 28714, 81275), body ending in a thin/sharp point (Ref. 2915, 81275). Pectoral fins reduced (Ref. 81275), 1.9-5.0 times in head length (Ref. 2915, 81275). Head naked, its length 5.6-6.9 times in SL; snout prominent (Ref. 2915, 81275). Mouth large and terminal; teeth strong, pointed or notched, aligned in a single row in both jaws, 12-16 in upper, 22-28 in lower jaw; premaxillae, as well as vomer and palatines, coalesced; maxillae, vomer and palatines toothless; eye very small, without a free margin (covered by skin); only the left gonad is developed and functional (Ref. 81275). Coloration: dark grey to almost black, darker posteriorly; belly whitish (Ref. 81275).

Biologi     Ordlista (t.ex. epibenthic)

Obligate air-breathing (Ref. 126274); Obligate air-breathing (Ref. 118411, 126274). Inhabits marginal vegetation and swamps constructing a flask-shaped nest in vegetation during the floods, which it is reputed to defend with vigour (Ref. 28714). Following flooding of the Gambia River banks, large elliptical floating nests are build in densely vegetated swamps at depths of about 1-1.5 m, in which about 1000 ‘amber-like’ eggs are laid; larvae hatch after 5 days (Ref. 10609). Feeds on crustaceans, insects and fish (Ref. 28714). No pelvic, anal or caudal fins (Ref. 28714). Possesses an electric organ that extends along almost the entire trunk to the tip of the tail (Ref. 10840). Also equipped with ampullary receptors and two types of tuberous receptors for electroreception (Ref. 10841). Showed increased electric organ discharge (EOD) rate by 50-60 Hz between 21 and 31°C (Ref. 10837).

Life cycle and mating behavior Maturities | Reproduktion | Spawnings | Egg(s) | Fecundities | Larver

Breeds in well-vegetated, marginal areas of swamps and rivers, where a large, floating nest, about 1 m in diameter, is constructed, in which the eggs are laid and later guarded by one of the parents (Ref. 27583). Distinct pairing (Ref. 205).

Main reference Upload your references | referenser | Koordinator | Medarbetare

Bigorne, R., 1990. Gymnarchidae. p. 185-186. In C. Lévêque, D. Paugy and G.G. Teugels (eds.) Faune des poissons d'eaux et saumâtres d'Afrique de l'Ouest. tome 1. Faune Trop. 28. Musée Royal de l'Afrique Centrale, Tervuren, Belgique and ORSTOM, Paris. (Ref. 2911)

IUCN Red List Status (Ref. 130435)

  Least Concern (LC) ; Date assessed: 12 May 2019

CITES (Ref. 128078)

Not Evaluated

CMS (Ref. 116361)

Not Evaluated

Threat to humans

  Harmless




Human uses

Fiskeri: kommersiell
FAO(Aquaculture systems: produktion; fiskeri: produktion; publication : search) | FishSource |

Ytterligare information

Trophic ecology
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Diet compositions
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Estimates based on models

Phylogenetic diversity index (Ref. 82804):  PD50 = 1.5000   [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00437 (0.00170 - 0.01121), b=3.08 (2.85 - 3.31), in cm Total Length, based on LWR estimates for this (Sub)family-body shape (Ref. 93245).
Trofisk nivå (Ref. 69278):  3.7   ±0.58 se; based on food items.
Resiliens (Ref. 120179):  Låg, lägsta populationsfördubblingstid 4,5-14 år (K=0.12-0.17).
Fishing Vulnerability (Ref. 59153):  High vulnerability (63 of 100).
Price category (Ref. 80766):   Unknown.