Brazil country information

Common names: [No common name]
Occurrence: native
Salinity: freshwater
Abundance: | Ref:
Importance: | Ref:
Aquaculture: | Ref:
Regulations: | Ref:
Uses: live export: yes;
Comments: Known only from the varzea floodplain at the conflluence of the Rio Solimoes (Amazon) and the Rio Japura in Mamiraua Reserve near the Tefé, Amazonas (Ref. 55508).
National Checklist:
Country Information: https://www.cia.gov/library/publications/resources/the-world-factbook/geos/br.html
National Fisheries Authority:
Occurrences: Occurrences Point map
Main Ref: Crampton, W.G.R., D.H. Thorsen and J.S. Albert, 2005
National Database:

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Classification / Names Common names | Synonyms | Catalog of Fishes(genus, species) | ITIS | CoL | WoRMS | Cloffa

Teleostei (teleosts) > Gymnotiformes (Knifefishes) > Gymnotidae (Naked-back knifefishes) > Gymnotinae
Etymology: Gymnotus: Greek, gymnos = naked (Ref. 45335); obscurus: Name from the Latin word 'obscurus' meaning dark, referring to its predominantly dark coloration..

Environment: milieu / climate zone / depth range / distribution range Ecology

Freshwater; benthopelagic. Tropical

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

South America: varzea floodplain at the conflluence of the Rio Solimoes (Amazon) and the Rio Japura in Mamiraua Reserve near the Tefé, Amazonas, Brazil.

Size / Weight / Age

Maturity: L_m ? range ? - ? cm
Max length : 21.5 cm TL male/unsexed; (Ref. 55508)

Short description Identification keys | Morphology | Morphometrics

Dorsal spines (total): 0; Dorsal soft rays (total): 0; Anal soft rays: 210 - 250. Distinguished from its congeners endemic to the Amazon and Orinoco Basins and the Guyana Shield in having many pectoral-fin rays 20-22; and a color pattern of oblique and undivided thin pale bands, less than one-quarter width of dark bands, with straight high-contrast margins, which extend to the dorsal midline on the anterior half of the body, and of which many are interrupted at the ventral margin of the hypaxial muscles along the anterior two-thirds of the body. Differs further from congeners endemic to the Amazon-Orinoco basins and the Guyana Shield in having the following unique combination of characters: clear (unpigmented) patch at the caudal end of the anal-fin membrane in specimens 6.0-23.5 TL; and bands never divided to form band pairs (Ref. 55508).

Facultative air-breathing in the genus (Ref. 126274); Inhabits root mats of floating meadows in floodplains. In the whitewater floodplain, juveniles are encountered in patches of floating macrophytes along lakes margins and along the edge of canos (drainage channels from lakes to the main river channels) and paranás (channels connected at both ends to the main river channel that transport whitewater through the floodplain). Floating macrophytes form extensive floating meadows. Undertakes aerial respiration by gulping atmospheric air into the hypervascularized posterior chamber of the gas bladder. Feeds primarily on chironomid larvae, small insect nymphs and small crustaceans (Ref. 55508).

Life cycle and mating behavior Maturities | Reproduction | Spawnings | Egg(s) | Fecundities | Larvae

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

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)

Least Concern (LC) ; Date assessed: 07 November 2018

CITES (Ref. 128078)

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=0.01000 (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).

Trophic level (Ref. 69278): 3.3 ±0.4 se; based on size and trophs of closest relatives

Resilience (Ref. 120179): High, minimum population doubling time less than 15 months (Preliminary K or Fecundity.).

Fishing Vulnerability (Ref. 59153): Low vulnerability (12 of 100).

Gymnotus obscurus Crampton, Thorsen & Albert, 2005