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 / djupintervall / distribution range
Ekologi
; sötvatten bentopelagisk. Tropical
South America: Amazon basin in Brazil and Peru.
Size / Vikt / Age
Könsmognad: Lm ? range ? - ? cm
Max length : 28.5 cm TL hane/ej könsbestämd; (Ref. 55508); publicerad maxvikt: 65.00 g (Ref. 55508)
Short description
Bestämningsnycklar | Morfologi | Morfometri
Taggstrålar i ryggfenan (totalt) : 0; Mjukstrålar i ryggfenan (totalt) : 0; Mjukstrålar i analfenan: 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
Könsmognad | Reproduktion | Lek | Ägg | Fecundity | Larver
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)
IUCN Red List Status (Ref. 130435: Version 2025-1)
Threat to humans
Harmless
Human uses
Verktyg
Special reports
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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=0.01000 (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).
Trofisk nivå (Ref.
69278): 3.2 ±0.40 se; based on food items.
Resiliens (Ref.
120179): Hög, lägsta populationsfördubblingstid mindre än 15 månader (Preliminary K or Fecundity.).
Fishing Vulnerability (Ref.
59153): Low vulnerability (19 of 100).
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