Actinopteri (ray-finned fishes) > Osteoglossiformes
(Bony tongues) > Mormyridae
Etymology: Hippopotamyrus: Greek, ippos = horse + Greek,potamos = river + greek, myros = the male of morey eel (Ref. 45335); longilateralis: The specific name longilateralis is in reference to the long lateral line (Ref. 85059).
Environment: milieu / climate zone / depth range / distribution range
Freshwater; benthopelagic. Tropical
Africa: Kunene River (Ref. 85059, 120641), from the Ruacana Falls downstream to above Epupa Falls, in Namibia (Ref. 85059) and Angola (Ref. 85059, 120641).
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 17.2 cm SL male/unsexed; (Ref. 85059)
Morphology | Morphometrics
soft rays: 22 - 25. Diagnosis: Hippopotamyrus longilateralis can be distinguished by following characters: distance from dorsal fin origin to end of caudal peduncle 37.9-41.7% of standard length; predorsal length 61.2-64.9% of standard length; distance from tip of snout to anal fin origin 59.0-62.7% of standard length; caudal peduncle length 19.5-22.0% of standard length; head length 19.2-22.8% of standard length; snout length 45.7-54.8% of head length; body depth 20.3-24.5% of standard length; number of dorsal fin rays 18-21; number of anal fin rays 22-25; number of scales in a linear series along the lateral line row 74-80; number of scales around caudal peduncle 19-22; and bipolar, pentaphasic waveform of EOD pulse (Ref. 85059).
Description Head broadly rounded with a terminally positioned mouth, lower jaw protruding less forward than upper; body long and slender, laterally compressed (Ref. 85059). Dorsal fin origin set far back and behind that of anal fin, situated about two-thirds of standard length from snout, obliquely orientated with anterior portion of the fin higher than the posterior portion; number of dorsal fin rays 18-21; anal fin opposite dorsal fin but origin further anterior and also obliquely orientated, anteriorly lower and posteriorly higher, margin broadly rounded; number of anal fin rays 22-25 (Ref. 85059). Scales cycloid with reticulate striae, except in centre, extending anteriorly to operculum and pectoral fins; scales around caudal peduncle 19-22 (Ref. 85059). Caudal peduncle slender and subcylindrical over the entire length, usually slightly less than one-fifth in standard length; tail fin with broadly rounded lobes (Ref. 85059). EOD bipolar and pentaphasic, duration of the two main phases about 230 µs but whole pulse may last up to 5 milliseconds because of weak pre- and post-potentials (Ref. 85059).
Colouration: Dark brown with a vertical black band from dorsal origin that is only weak in most specimens (Ref. 85059). Colour in preservation dark to medium brown, often with milky-grey hue, especially where opaque 'mormyrid skin' is present (Ref. 85059).
Found along well-vegetated and steep banks of the river; they therefore possibly prefer undercut banks with structure such as roots (Ref. 85059).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Kramer, B. and E.R. Swartz, 2010. A new species of Slender Stonebasher within the Hippopotamyrus ansorgii complex from the Cunene River in southern Africa (Teleostei: Mormyriformes). J. Nat. Hist. 44(35-36):2213-2242. (Ref. 85059)
IUCN Red List Status (Ref. 123251)
CITES (Ref. 123416)
Threat to humans
Common namesSynonymsMetabolismPredatorsEcotoxicologyReproductionMaturitySpawningSpawning aggregationFecundityEggsEgg development
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingMass conversion
Estimates based on models
Phylogenetic diversity index (Ref. 82805
= 0.5002 [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
): 3.2 ±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.).
Vulnerability (Ref. 59153
): Low vulnerability (21 of 100) .