Classification / Names
Common names | Synonyms | Catalog of Fishes (gen., sp.) | ITIS | CoL | WoRMS | Cloffa
Actinopterygii (ray-finned fishes) > Gymnotiformes
(Knifefishes) > Hypopomidae
Etymology: Hypopygus: Greek, hypo = under + Greek, pyge = tail (Ref. 45335); nijsseni: The specific epithet, nijsseni, is a patronym in honour of Hans Nijssen for his contribution to Neotropical ichthyology (Ref. 88778).
Environment: milieu / climate zone / depth range / distribution range
Freshwater; benthopelagic. Tropical
South America: Hypopygus nijsseni is known only from small streams in the vicinity of Tefé (Ref. 88778).
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 9.6 cm TL male/unsexed; (Ref. 88778)
Morphology | Morphometrics
Hypopygus nijsseni is diagnosed from congeners by the following combination of characters: the total number of anal-fin rays (145–152 versus 102–135 in H. hoedemani, H. lepturus, and H. minissimus; 155–174 in H. cryptogenes), the presence of the sixth infraorbital bone (versus absence in H. hoedemani, H. lepturus, and H. minissimus), the presence of oblique bands (versus absence in H. minissimus), the presence of scales at midbody (versus absence in H. minissimus), the dorsal rami of intermittent branch of anterior lateral line nerve visible as two black parallel lines (versus not visible in H. ortegai), the head length (13.2–15.3% of LEA versus 12.6–13.9 in H. ortegai), the distance at the nape (12.5–13.8% of LEA versus 11.0–12.5 in H. ortegai), the total number of pectoral fin rays (ten to 12 versus 12–16 in H. isbruckeri), the number of scales above the lateral line (five to six versus seven to eight in H. isbruckeri), and the distance from the anus to the anal fin (7.9–9.4% of LEA versus 10.0–12.0 in H. neblinae) (Ref. 88778).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
de Santana, C.D. and W.G.R. Crampton, 2011. Phylogenetic interrelationships, taxonomy, and reductive evolution in the Neotropical electric fish genus Hypopygus (Teleostei, Ostariophysi, Gymnotiformes). Zool. J. Linn. Soc. 163:1096-1156. (Ref. 88778)
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
= 0.5039 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00372 (0.00140 - 0.00985), b=3.06 (2.83 - 3.29), in cm Total Length, based on LWR estimates for this (Sub)family-body shape (Ref. 93245
Trophic Level (Ref. 69278
): 3.1 ±0.4 se; Based on size and trophs of closest relatives
Resilience (Ref. 69278
): High, minimum population doubling time less than 15 months ().
Vulnerability (Ref. 59153
): Low vulnerability (10 of 100) .