Gymnarchus niloticus, Aba : fisheries

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Gymnarchus niloticus Cuvier, 1829

Aba
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Gymnarchus niloticus
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Classification / Names Common names | Synonyms | Catalog of Fishes(genus, species) | ITIS | CoL | WoRMS | Cloffa

Teleostei (teleosts) > 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 Ecology

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

Distribution Countries | FAO areas | Ecosystems | Occurrences | Point map | Introductions | 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 / Weight / Age

Maturity: Lm ?  range ? - ? cm
Max length : 167 cm SL male/unsexed; (Ref. 2915); max. published weight: 18.5 kg (Ref. 2915)

Short description Morphology | Morphometrics

Dorsal spines (total): 0; Dorsal soft rays (total): 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).

Biology     Glossary (e.g. 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 Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae

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 | References | Coordinator | Collaborators

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

Not Evaluated

CMS (Ref. 116361)

Not Evaluated

Threat to humans

  Harmless





Human uses

Fisheries: commercial
FAO - Aquaculture: production; Fisheries: landings; Publication: search | FishSource |

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Internet sources

AFORO (otoliths) | Aquatic Commons | BHL | Cloffa | BOLDSystems | Websites from users | Check FishWatcher | CISTI | Catalog of Fishes: genus, species | DiscoverLife | ECOTOX | FAO - Aquaculture: production; Fisheries: landings; Publication: search | Faunafri | Fishipedia | Fishtrace | GenBank: genome, nucleotide | GloBI | Google Books | Google Scholar | Google | IGFA World Record | MitoFish | Otolith Atlas of Taiwan Fishes | Public aquariums | PubMed | Reef Life Survey | Socotra Atlas | Tree of Life | Wikipedia: Go, Search | World Records Freshwater Fishing | Zoobank | Zoological Record

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).
Trophic level (Ref. 69278):  3.7   ±0.58 se; based on food items.
Generation time: 6.5 ( na - na) years. Estimated as median ln(3)/K based on 1 growth studies.
Resilience (Ref. 120179):  Low, minimum population doubling time 4.5 - 14 years (K=0.12-0.17).
Fishing Vulnerability (Ref. 59153):  High vulnerability (63 of 100).
Price category (Ref. 80766):   Unknown.
Nutrients (Ref. 124155):  Calcium = 62.6 [33.3, 136.7] mg/100g; Iron = 1.01 [0.56, 2.07] mg/100g; Protein = 17.4 [15.5, 19.1] %; Omega3 = 0.27 [0.11, 0.68] g/100g; Selenium = 118 [43, 271] μg/100g; VitaminA = 17 [6, 45] μg/100g; Zinc = 1.05 [0.73, 1.57] mg/100g (wet weight);