Actinopterygii (ray-finned fishes) > Characiformes
(Characins) > Distichodontidae
Etymology: Nannocharax: Latin, nannus = small + Greek, charax = a marine fish without identification (Ref. 45335); usongo: Named in honor of Dr. Leonard Usongo, highly successful conservation biologist and supporter of numerous fish inventories in Cameroon (Ref. 80507).
Environment: milieu / climate zone / depth range / distribution range
Freshwater; benthopelagic. Tropical; 6°N - 5°N, 6°E - 10°E
Africa: Cross River and Niger Delta (Ref. 80507).
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 4.4 cm SL male/unsexed; (Ref. 80507)
Morphology | Morphometrics
soft rays: 10 - 12. Diagnosis: Nannocharax usongo is distinguished from all other described Nannocharax species by its very small distance between the posterior border of the anus and the articulation of first anal-fin ray (0.9–1.9 vs. 2.2–14.2% of standard length), its body coloration, which consist of 7–11 mostly big blotches along the lateral line often coalesced to one wide black band, and 7–12 small blotches along the dorsum (Ref. 80507).
Type specimens collected on logs in areas of relatively rapid water movement; logs had a very rugged surface due to being partially decomposed by wood eating Povilla (Ephemeroptera) larvae; individuals were spaced singly and moved very rapidly around log surface, but always with close contact to it and never reaching out into the free water column; first ray of pelvic fin very thick, which is adaptation to cling on wood in strong current; mouth subinferior and blunt (Ref. 80507).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Dunz, A.R. and U.K. Schliewen, 2009. Description of two new species of Nannocharax Günther, 1867 (Teleostei: Characiformes: Distichodontidae) from the Cross River, Cameroon. Zootaxa 2028:1-19. (Ref. 80507)
IUCN Red List Status (Ref. 119314)
CITES (Ref. 115941)
Threat to humans
Common namesSynonymsMetabolismPredatorsEcotoxicologyReproductionMaturitySpawningSpawning aggregationFecundityEggsEgg development
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingMass conversion
Estimates of some properties based on models
Phylogenetic diversity index (Ref. 82805
= 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00380 (0.00147 - 0.00981), b=3.11 (2.88 - 3.34), 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 (Preliminary K or Fecundity.).
Vulnerability (Ref. 59153
): Low vulnerability (10 of 100) .