Taxonomy & naming
Clavocharax notospilus was originally described by Jacques Pellegrin in 1930, from a type specimen collected at 'La Passa, Haut Ogôoué' — a locality in the upper Ogowe River system of what is now Gabon. The species epithet notospilus combines the Greek nōtos (back or dorsal surface) and spilos (spot or blotch), referencing the diagnostic dark marking on the lower caudal peduncle.
The genus Brachypetersius belongs to the tribe Petersiini within the family Alestidae (African tetras). Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) records the valid combination as Clavocharax notospilus (Pellegrin, 1930), with the parenthetical authority reflecting its original placement in a different genus before transfer to Brachypetersius. The tribe Petersiini comprises several small-to-medium alestids distributed across West and Central African river systems; Brachypetersius is a relatively species-poor genus and C. notospilus is one of its more range-restricted members, confined to two adjacent coastal-basin river systems.
Diagnostic characters that distinguish C. notospilus from congeners include the dark peduncular blotch (present but not sharply defined on the ventral surface of the caudal peduncle), the absence of a humeral spot, a lateral-line scale count of 29 + 2, 5½ scales between the lateral line and the dorsal-fin origin, and an anal-fin formula of III,16–17.
This fish was long listed as Brachypetersius notospilus; Eschmeyer's Catalog of Fishes places the species in Clavocharax, and the current combination Clavocharax notospilus is followed here.
Morphology
Clavocharax notospilus is a small, moderately elongate tetra reaching a maximum of around 2.9 in total length (FishBase) or 3.19 in standard length (Faunafri/MNHN-MRAC-IRD). Body depth is 2.6–2.9 times into standard length; head length is 3.55–3.75 times into standard length, indicating a relatively slender body and smallish head typical of the petersiine tribe.
Meristics from the Faunafri reference database (MNHN/MRAC/IRD) give an anal fin of III,16–17 rays with a total ray count cited as 18–21 in some literature sources; the lateral line carries 28–30 pored scales (29 + 2 total). Scale rows between the lateral line and the dorsal-fin origin number 5½. Dentition follows the alestid pattern with a multicuspid dental formula.
The species' colour pattern in life is poorly documented in the published literature, but preserved material shows the diagnostic features: a dark, not sharply delimited blotch on the lower surface of the caudal peduncle, and no humeral spot — both characters useful in distinguishing it from related Brachypetersius species. Whether it displays the flank iridescence or red or yellow fin pigmentation common in some alestids is not confirmed in available sources.
Habitat
The species is a Lower Guinea endemic, known from two adjacent coastal-basin river systems: the Kouilou River basin in the Republic of Congo and the Ogowe (Ogôoué) River basin of Gabon. The type locality, 'La Passa, Haut Ogôoué,' places the original collection in the upper Ogowe drainage of Gabon. FishBase categorises the species as a pelagic freshwater fish, suggesting it is a water-column inhabitant rather than a benthic or marginal species.
The Kouilou and Ogowe systems drain humid tropical lowland and sub-montane rainforest in a subregion whose watersheds are characterised by clear, often softly acidic rivers running through lateritic soils and dense forest cover. Commercial logging, extensive in this region over the past several decades, has increased sedimentation loads in many smaller tributaries — identified by the IUCN as the primary threat to the species. Whether C. notospilus is a clear-water specialist vulnerable to turbidity or a generalist capable of tolerating some sedimentation is not established in the literature.
Feeding
No specific diet data for Clavocharax notospilus has been published in the accessible literature. By analogy with related petersiine alestids — small-bodied, midwater tetras of West-Central African rivers — the diet is likely omnivorous and opportunistic, combining small aquatic invertebrates (insect larvae, micro-crustaceans), terrestrial insects that fall to the water surface, and possibly plant material or detritus.
In the aquarium, alestids of comparable size generally accept a varied diet of good-quality flake or micro-pellets supplemented with frozen or live foods such as Daphnia, Artemia nauplii, and chironomid larvae. Given the data-sparse nature of this species in both the wild and captivity, generalising from its tribe is the most defensible approach; direct observations of wild feeding behaviour have not been reported.
Mating
No mating observations for Clavocharax notospilus have been published. Within Alestidae, and particularly the Petersiini, the typical reproductive guild is egg-scattering open spawning: males court females in open water or among fine-leaved aquatic vegetation, and pairs release adhesive or semi-adhesive eggs that drift or adhere to submerged plant matter. No parental care is shown by any closely related petersiine species.
Sexual dimorphism in C. notospilus has not been characterised in available sources. As in most small alestids, females may be more robust-bodied when gravid, and males may show more intense pigmentation or fin extension during courtship, but these features have not been formally documented for this species.
Breeding
Captive breeding of Clavocharax notospilus has not been reported in the hobbyist or scientific literature accessible for this account. The species is not known to be established in the ornamental-fish trade. Based on the reproductive pattern of the broader Petersiini tribe, spawning would be expected to occur over fine-leaved plants or similar substrates, with small adhesive eggs and no parental care; adults would be expected to consume eggs if left in the spawning vessel.
Given the species' restricted distribution and the absence of an established captive population, the breeding biology remains undescribed. Any hobbyist maintaining specimens should treat them as conservation-significant animals and document breeding attempts carefully.
In the aquarium
Clavocharax notospilus is not established in the ornamental-fish trade and is essentially unknown in the hobby. It has not been the subject of aquarium husbandry accounts in any accessible hobby literature. Information on its care requirements in captivity is therefore largely inferential, extrapolated from the needs of related West-Central African alestids.
If kept, a small school in a well-filtered, planted aquarium with soft to moderately hard, slightly acidic to neutral water would suit the conditions of its native Ogowe and Kouilou river drainages. Water temperatures in the range of 72–79 °F (72–79 °F) are typical for Gabonese lowland rivers. A varied diet including live and frozen invertebrates would be appropriate. Given the species' data-deficient conservation status and restricted range, wild specimens should be regarded as potentially vulnerable; any animals offered in trade would warrant provenance verification.
Conservation
Clavocharax notospilus was assessed by the IUCN in 2009 and placed in the Data Deficient (DD) category. The assessment notes that the species comes from 'very poorly sampled/surveyed areas' and that it may be more widespread than current collecting records indicate, making a formal threat categorisation premature. More information on its actual distribution is required before it can be assessed against threat criteria.
The primary documented threat is intensive commercial logging in the Kouilou and Ogowe basins, which generates elevated sedimentation and associated water-quality degradation in forest rivers. The Lower Guinea coastal zone has among the highest rates of timber extraction in Central Africa, and many smaller river systems in this region have experienced significant habitat alteration since the 1990s. Without targeted surveys to establish the species' actual range and population status, it is impossible to judge whether those pressures have materially affected C. notospilus — which is precisely the information gap the DD listing records.