Classification / Names
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Gymnotiformes (Knifefishes) >
Gymnotidae (Naked-back knifefishes) > Gymnotinae
Etymology: Gymnotus: Greek, gymnos = naked (Ref. 45335); arapaima: Named for the pirarucu Arapaima gigas (Teleostei: Osteoglossomorpha), referring to the elongate and slightly depressed head, which it resembles. Noun in apposition..
Environment: milieu / climate zone / depth range / distribution range
Ecologia
; acqua dolce demersale; pH range: 6.3 - 7.2. Subtropical
South America: Mamirauá lake system, Lago Tefé, and terra firme swamps near the town of Tefé in Central Amazonia.
Size / Peso / Age
Maturity: Lm ?  range ? - ? cm
Max length : 55.0 cm TL maschio/sesso non determinato; (Ref. 41292); peso massimo pubblicato: 450.00 g (Ref. 41292)
Short description
Chiavi di identificazione | Morfologia | Morfometria
Possess reverse counter shading (lighter on top) in which the dark bands are interrupted dorsally and the pale interband regions merge on the dorsum and in which the dorsum has a silver-blue sheen in life, and very large anterior nares (diameter about that of eye), associated with a large cleft in the anterolateral margin of the ethmoid region resulting in a square anterior margin of snout between the anterior nares. With deep body (body depth 11-13% TL versus 6-10): long head (head length 12.7-13.6% TL versus 8.8-12.6), and depressed head (head depth 53-57% TL versus 58-64) (Ref. 41292).
Facultative air-breathing in the genus (Ref. 126274); Juveniles commonly collected in várzea floating meadows, adults in várzea flooded forest but rarely caught in floating meadows where they are presumed to spawn.
Life cycle and mating behavior
Maturities | Riproduzione | Spawnings | Egg(s) | Fecundities | Larve
Albert, J.S. and W.G.R. Crampton, 2001. Five new species of Gymnotus (Teleostei: Gymnotiformes) from an upper Amazon floodplain, with descriptions of electric organ discharges and ecology. Ichthyol. Explor. Freshwat. 12(3):241-266. (Ref. 41292)
IUCN Red List Status (Ref. 130435)
Threat to humans
Harmless
Human uses
Strumenti
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Estimates based on models
Phylogenetic diversity index (Ref.
82804): PD
50 = 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00437 (0.00209 - 0.00911), b=2.98 (2.79 - 3.17), in cm total length, based on LWR estimates for this (Sub)family-body shape (Ref.
93245).
Trophic level (Ref.
69278): 3.2 ±0.40 se; based on food items.
Resilienza (Ref.
120179): Medio, tempo minimo di raddoppiamento della popolazione 1.4 - 4.4 anni (Preliminary K or Fecundity.).
Fishing Vulnerability (Ref.
59153): Moderate vulnerability (42 of 100).