Classification / Names
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Gymnotiformes (Knifefishes) >
Gymnotidae (Naked-back knifefishes) > Gymnotinae
Etymology: Gymnotus: Greek, gymnos = naked (Ref. 45335); varzea: Named for the whitewater várzea floodplain, which this species is restricted to..
Environment: milieu / climate zone / depth range / distribution range
Écologie
; eau douce benthopélagique. Tropical
South America: Amazon basin in Brazil and Peru.
Taille / Poids / Âge
Maturity: Lm ? range ? - ? cm
Max length : 28.5 cm TL mâle / non sexé; (Ref. 55508); poids max. publié: 65.00 g (Ref. 55508)
Description synthétique
Clés d'identification | Morphologie | Morphométrie
Épines dorsales (Total) : 0; Rayons mous dorsaux (Total) : 0; Rayons mous anaux: 230 - 310. Distinguished from its congeners endemic to the Amazon and Orinoco Basins and the Guyana Shield in having a color pattern of 16-22 oblique dark pigment bands with wavy and irregular margins in which the majority of bands at midbody form X-shaped patterns (resembling metaphase chromosomes) and in which the dark bands are about twice as broad as the pale interbands. Further differs from its congeners in having the following unique combination of characters: clear (unpigmented) patch at the caudal end of the anal-fin membrane in specimens 6.0-23.7 cm; and bands never divided to form band pairs (Ref. 55508).
Facultative air-breathing in the genus (Ref. 126274); Found in root mats of floating meadows in floodplains (Ref. 55508). Gulps atmospheric air into the hypervascularized posterior chamber of its gas bladder (Ref. 55508). Feeds on small aquatic invertebrates such as chironomid larvae, insect nymphs and microcrustaceans (Ref. 55508).
Life cycle and mating behavior
Maturities | Reproduction | Spawnings | Egg(s) | Fecundities | Larves
Crampton, W.G.R., D.H. Thorsen and J.S. Albert, 2005. Three new species from a diverse, sympatric assemblage of the electric fish Gymnotus (Gymnotiformes: Gymnotidae) in the lowland Amazon basin, with notes on ecology. Copeia 2005(1):82-99. (Ref. 55508)
Statut dans la liste rouge de l'IUCN (Ref. 130435)
Menace pour l'homme
Harmless
Utilisations par l'homme
Outils
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Sources Internet
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=0.01000 (0.00244 - 0.04107), b=3.04 (2.81 - 3.27), in cm total length, based on all LWR estimates for this body shape (Ref.
93245).
Niveau trophique (Ref.
69278): 3.2 ±0.40 se; based on food items.
Résilience (Ref.
120179): Haut, temps minimum de doublement de population inférieur à 15 mois (Preliminary K or Fecundity.).
Fishing Vulnerability (Ref.
59153): Low vulnerability (19 of 100).
