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Teleostei (teleosts) > 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 Ecology

Freshwater; demersal; pH range: 6.3 - 7.2. Subtropical

Distribution Countries | FAO areas | Ecosystems | Occurrences | Point map | Introductions | Faunafri

South America: Mamirauá lake system, Lago Tefé, and terra firme swamps near the town of Tefé in Central Amazonia.

Size / Weight / Age

Maturity: L_m ? range ? - ? cm
Max length : 55.0 cm TL male/unsexed; (Ref. 41292); max. published weight: 450.00 g (Ref. 41292)

Short description Identification keys | Morphology | Morphometrics

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 | Reproduction | Spawnings | Egg(s) | Fecundities | Larvae

Main reference Upload your references | References | Coordinator : Campos-da-Paz, Ricardo | Collaborators

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)

Least Concern (LC) ; Date assessed: 12 August 2020

CITES

Not Evaluated

CMS (Ref. 116361)

Not Evaluated

Threat to humans

Harmless

Human uses

FAO - Publication: search | FishSource |

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Estimates based on models

Phylogenetic diversity index (Ref. 82804): PD₅₀ = 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.

Resilience (Ref. 120179): Medium, minimum population doubling time 1.4 - 4.4 years (Preliminary K or Fecundity.).

Fishing Vulnerability (Ref. 59153): Moderate vulnerability (42 of 100).

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Gymnotus arapaima Albert & Crampton, 2001