Taxonomy & naming
Citharidium ansorgii was described by the Belgian-British ichthyologist George Albert Boulenger in 1902, and it remains the only recognised species in the genus Citharidium. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) treats Citharidium ansorgii Boulenger, 1902 as the valid name, placed in the family Citharinidae — a small family of deep-bodied African characiforms sometimes called "lutefishes", distinct from the related but much larger Distichodontidae (Distichodus and allies).
Because the species is so rarely encountered outside fisheries surveys and museum collections, it is easy to confuse in casual references with the more commonly cited citharinid genus Citharinus, which shares a similar deep-bodied, grazing body plan; Citharidium is distinguished by characters detailed in Boulenger's original description and subsequent revisions of the family. The genus and species name have not been revised since description, and no synonyms are in wide use.
Morphology
Citharidium ansorgii is a large, laterally compressed, deep-bodied fish consistent with the citharinid body plan — built for steady cruising and substrate/detritus grazing rather than fast predatory pursuit. FishBase records a maximum published length of 23 in standard length, with a total length of 27.5 in reported, and a maximum weight of 9.1 kg, making it one of the larger species in its family and a substantial food fish where it occurs.
Detailed published data on colouration, fin structure and other external characters specific to this species is sparse in the sources available; general citharinid morphology features a small, subterminal or underslung mouth suited to grazing, and a deep, silvery body typical of open-water to demersal riverine fishes. Prospective keepers and researchers should treat unconfirmed colour or pattern descriptions with caution given how little photographic and field documentation exists for this species.
Habitat
The species is native to West and Central Africa, documented from the Niger River basin in Nigeria and from the Bénoué (Benue) and Chad basin drainages in Cameroon. It is a demersal, tropical freshwater fish, associated with the main channels and floodplain habitats typical of these large African river systems rather than small headwater streams.
Specific water-chemistry data (temperature range, pH) for Citharidium ansorgii is not available in the sources reviewed here; broadly, the Niger and Bénoué-Chad basins run warm year-round with strong seasonal flood-and-drought hydrology, and citharinids in these systems are typically found in main-channel and floodplain waters rather than blackwater tributaries. Data is sparse enough that specific figures should not be assumed rather than sourced.
Feeding
FishBase records Citharidium ansorgii with an omnivorous trophic level of 2.1, consistent with the citharinid family's general grazing habit — feeding on algae, detritus, plant material and small invertebrates picked from the substrate rather than active predation on other fish. This places it much closer to a herbivore/grazer than to a predatory characin.
No aquarium-specific feeding data exists for this species given its near-total absence from the hobby; a diet mirroring its wild grazing habits — vegetable matter, algae-based foods and some protein — would be the biologically consistent approach for any fish this size kept in captivity, though this is inference from family-level diet rather than documented aquarium practice for the species itself.
Mating
No courtship or pairing behaviour has been documented for Citharidium ansorgii in the sources reviewed here. Citharinids as a family are not known for elaborate courtship display, and given the complete absence of aquarium-breeding accounts for this species, nothing further can be said without speculating beyond the available record.
Breeding
Breeding biology for Citharidium ansorgii is essentially undocumented. Its relatives in Citharinidae and the closely related Distichodontidae are generally egg-scatterers that are rarely, if ever, bred in captivity, and there is no evidence in the available literature of aquarium or hatchery breeding of this species specifically. Given its large adult size and demersal riverine habits, any reproduction is presumed to follow the broad open-water spawning pattern typical of large African river characiforms, but this is inference rather than a documented mode — it should not be reported as established fact.
In the aquarium
Citharidium ansorgii is not a hobby aquarium fish in any meaningful sense: with a documented maximum length near 23.5 in SL (roughly 27.5 in total length) and a weight of up to 9.1 kg, it is a large food-fish-scale species entirely unsuited to home aquaria, and it does not appear in aquarium trade literature or hobbyist care guides. Anyone encountering the species is far more likely to do so through fisheries or museum contexts than through the ornamental fish trade.
Where very large public-aquarium or research holdings might house a species like this, the space, filtration and social requirements would need to scale to a multi-hundred-kilogram-biomass fish similar in scope to the larger Distichodus and Citharinus species, with the same caution against ever attempting to keep or release such a fish in an inadequate home setup.
Conservation
The IUCN Red List assesses Citharidium ansorgii as Data Deficient (2019), noting that the species is known only from the Niger basin and reflecting how little targeted study its population status has received; some older sources cited Least Concern, but the current assessment supersedes that. Documented threats within its known range include oil exploration activity in the Niger Delta and the spread of invasive water hyacinth in the Niger inland delta, both pressures on the broader river system rather than confirmed population-level impacts on this species specifically.
Because it is not a significant aquarium-trade species, collection pressure from the ornamental fish trade is not a relevant conservation factor here; the primary concerns are habitat degradation and water-quality pressures affecting the Niger and Bénoué-Chad river systems more broadly.