Classification / Names
Common names | Synonyms | Catalog of Fishes (gen., sp.) | ITIS | CoL | WoRMS | Cloffa
Actinopterygii (ray-finned fishes) > Characiformes
(Characins) > Crenuchidae
(South American darters) > Characidiinae
Etymology: Characidium: Diminutive of Charax, -akos = a fish without identification (Ref. 45335); helmeri: Named for Dr. José Luis Helmer, who collected part of the material of the species and in recognition of his pioneer studies on the natural history of the freshwater fishes in Espírito Santo and Southern Bahia, since 1976. A genitive noun.
Environment: milieu / climate zone / depth range / distribution range
Freshwater; benthopelagic. Tropical
South America: Brazil.
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 4.0 cm SL male/unsexed; (Ref. 104900)
Morphology | Morphometrics
soft rays: 7 - 9;
Vertebrae: 33 - 35. Characidium helmeri is distinguished from other species of Characidium by possessing dark, vertically elongated, irregular, narrow spots or dashes, usually more evident over the midlateral stripe and/or ventral half of body, formed by high concentration of melanophores on the posterior half of scales, occurring in a somewhat curved or zigzag-shape. It also differs from congeners by having extremely reduced or complete absence of supraorbital. It further differs by having lateral line reduced (vs. complete, except in C. bahiense, C. interruptum, C. laterale, C. mirim, C. nupelia, C. rachovii, C. stigmosum and C. xavante), adipose fin absent (vs. present, except in C. mirim, C. nupelia, C. stigmosum, and C. xavante), and isthmus naked on its anteriormost portion (vs. isthmus completely covered by scales in most congeners, except in C. alipioi, C. boavistae, C. crandellii, C. declivirostre, C. fasciatum, C. gomesi, C. grajahuensis, C. japuhybense, C. lauroi, C. macrolepidotum, C. oiticicai, C. schubarti, C. timbuiense, and C. vidali). It can be diagnosed from C. bahiense, C. interruptum, C. laterale, C. mirim, C. nupelia, C. rachovii and C. xavante by having more pored lateral line scales 13-22 (vs. 5-11) and two series of dentary teeth (vs. one). It can be further separated from C. nupelia and C. xavante by the absence of a dark humeral blotch (vs. presence) smaller number of dark vertical bars on the body, 7-12 when present (vs. 12-18). It is distinct from C. vestigipinne, a species with adipose fin absent or reduced, by having two dentary rows of teeth, the outer with tricuspid teeth (vs. one row of conical teeth), 4 scales above lateral line and 4 below (vs. 5 above; and 5 or 6 below), and absence of roundish black marks on pelvic, dorsal, and anal fins (vs. presence). It further differs from C. stigmosum by having a black basicaudal dot (vs. absence), and by having pelvic, pectoral, anal, and caudal fins not dark pigmented in males (vs. pigmented) (Ref. 104900).
Occurs only in slow flowing river stretches, situated 8-91m above sea level, a few centimeters to 1.5 m deep, with transparent or dark water running in substrate composed of pebbles, gravel, or organic debris. Found syntopic with Aspidoras virgulatus Nijssen & Isbrucker, Astyanax sp., Geophagus brasiliensis (Quoy & Gaimard), Hoplerythrinus uniaeniatus (Agassiz), Hoplias malabaricus (Bloch), Mimagoniates microlepis Steindachner, M. sylvicola Menezes & Weitzman, Scleromystax prionotos (Nijssen &
Isbrucker), Otothyris travassosi Britski & Schaefer, Phalloceros ocellatus Lucinda, including the endangered species Acentronichthys leptos Eigenmann & Eigenmann and Rachoviscus graciliceps Weitzman & Cruz. Food items in the stomach contents of four specimens ranging from 2.68-3.59 cm SL consisted of small aquatic insect larvae, mainly Chironomidae, nymphs, fragments of insects, vegetable debris and organic matter partially digested (Ref. 104900).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Zanata, A.M., L.M. Sarmento-Soares and R.F. Martins-Pinheiro, 2015. A new species of Characidium Reinhardt (Ostariophysi: Characiformes: Crenuchidae) from coastal rivers in the extreme south of Bahia, Brazil. Zootaxa 4040(3):371-383. (Ref. 104900)
IUCN Red List Status (Ref. 120744)
CITES (Ref. 118484)
Threat to humans
Common namesSynonymsMetabolismPredatorsEcotoxicologyReproductionMaturitySpawningSpawning aggregationFecundityEggsEgg development
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingMass conversion
Estimates based on models
Phylogenetic diversity index (Ref. 82805
= 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.01122 (0.00514 - 0.02450), b=3.04 (2.87 - 3.21), in cm Total Length, based on all LWR estimates for this body shape (Ref. 93245
Trophic Level (Ref. 69278
): 3.3 ±0.3 se; Based on size and trophs of closest relatives
Vulnerability (Ref. 59153
): Low vulnerability (10 of 100) .