Classification / Names
Common names | Synonyms | Catalog of Fishes (gen., sp.) | ITIS | CoL | WoRMS | Cloffa
Actinopterygii (ray-finned fishes) > Gymnotiformes
(Knifefishes) > Gymnotidae
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
Freshwater; demersal; 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 / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 55.0 cm TL male/unsexed; (Ref. 41292); max. published weight: 450.00 g (Ref. 41292)
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).
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
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
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. 115185)
CITES (Ref. 115941)
Threat to humans
Common namesSynonymsMetabolismPredatorsEcotoxicologyReproductionMaturitySpawningFecundityEggsEgg development
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingMass conversion
Estimates of some properties based on models
Phylogenetic diversity index (Ref. 82805
= 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00417 (0.00193 - 0.00902), b=3.04 (2.84 - 3.24), 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. 69278
): Medium, minimum population doubling time 1.4 - 4.4 years (Preliminary K or Fecundity.).
Vulnerability (Ref. 59153
): Moderate vulnerability (38 of 100) .