Taxonomy & naming
Distichodus notospilus was described by the German-British ichthyologist Albert Günther in 1867. It belongs to the family Distichodontidae — the African distichodontids, a characiform lineage largely restricted to Africa and separate from the American piranha-and-pacu family Serrasalmidae despite superficial resemblance in some relatives. The genus Distichodus is the largest in the family, ranging from small, peaceful nano species to the much larger, heavy-bodied D. sexfasciatus and D. lusosso; the Catalog of Fishes (Eschmeyer, California Academy of Sciences) is the governing authority for the valid name and continues to treat notospilus as a distinct, valid species within the genus.
A 2020 integrative taxonomy study (published in Zootaxa) using cast-net sampling across Central African river systems examined D. notospilus populations and found endemism patterns consistent with the species' distribution across the Lower Guinea ichthyofaunal province and the western tributaries of the middle and lower Congo, reinforcing its status as a genuine, geographically coherent species rather than a species complex. The common trade name "longsnout distichodus" refers to the genus's characteristically elongated, tubular snout with a small, downward-pointing mouth.
Morphology
Distichodus notospilus has the elongate, moderately compressed body typical of the genus, with a pointed, tapering snout and a small, underslung mouth set well back from the tip — an arrangement built for grazing surfaces rather than seizing prey. FishBase records a maximum length of 7.5 in, modest by the standards of the larger Distichodus species and well short of the near-meter size some hobbyists mistakenly associate with the family. The dorsal fin carries 15–18 soft rays and the anal fin 12–15 soft rays, set well back on the body, giving the fish a streamlined profile suited to holding position in flowing water.
Colouration is silvery, often with the darker markings and banding typical of Distichodus species, though the cache did not preserve a detailed colour description; as with most of the genus, intensity and pattern can shift somewhat with mood and water conditions. Sexual dimorphism is not documented for this species.
Habitat
Distichodus notospilus is native to coastal river basins of west-central Africa, with a range spanning from the Sanaga River in Cameroon south to the Chiloango in Angola, and extending into the middle and lower Congo River basin. Within that range it is associated with the Lower Guinea ichthyofaunal province, a biogeographically distinct zone of coastal drainages independent of the main Congo channel, as well as western tributaries feeding into the middle and lower Congo itself.
FishBase classifies the species as tropical freshwater and pelagic, with a preferred temperature range of roughly 73–81 °F — warm, typical West and Central African river conditions. The cache does not provide specific pH or hardness data for this species; as with related Distichodus and other Lower Guinea/Congo-basin characins, water is generally soft to moderately mineralised and can be tannin-influenced in blackwater tributaries, though this species' exact chemistry preferences are not well documented and should not be over-generalised from more blackwater-associated Congo fish.
Feeding
Distichodus notospilus is an omnivore whose diet leans heavily toward plant matter, consistent with the genus as a whole: in the wild it grazes algae, soft aquatic vegetation and detritus, using its small, downturned mouth to crop surfaces rather than pursue prey. Aquarium care sources describe the genus's feeding needs as centred on vegetable foods — spirulina-based flakes and pellets, blanched vegetables, and soft plant matter — supplemented with occasional prepared or protein foods, but never as a primary meat-based diet.
A fish fed only protein-rich foods and denied vegetable matter is prone to nutritional problems and, notably, to redirecting its grazing instinct onto tank plants and even other fish's fins, so a plant-forward diet is both a health requirement and a practical way to reduce damage to aquarium furnishings and tankmates.
Mating
Courtship and spawning behaviour for Distichodus notospilus has not been documented in the aquarium hobby or in the available literature. Like other Distichodus species, it is believed — by analogy with related large Congo-basin and Lower Guinea characins — to undertake upriver spawning migrations timed to the onset of the rainy season, a pattern documented more thoroughly in some related large-river characiforms than in this species specifically. No reliable account of pairing behaviour, courtship display or external sexual dimorphism exists for this species; the cache found no such data, and none should be assumed.
Breeding
Distichodus notospilus has, as far as documented sources indicate, never been bred in captivity. Aquarium and care-guide sources describe the genus generally as egg-scatterers, but for this species specifically there is no confirmed spawning account, no known rearing method and no established hobby or commercial breeding — the working assumption, shared across most Distichodus species, is that reproduction depends on the long-distance upriver migration and rainy-season triggers of its wild river habitat, conditions essentially impossible to replicate in a home aquarium.
Prospective keepers should treat this species as effectively unbreedable at home and should not expect fry from captive stock; all specimens in the trade are wild-collected or, at best, farmed under conditions not disclosed in available sources.
In the aquarium
Distichodus notospilus is a modestly sized characin at a maximum recorded length of 7.5 in, considerably smaller and more manageable than the giant Distichodus species sometimes confused with it, but it still needs a spacious, long aquarium with strong water movement and excellent filtration to mimic its native river habitat. Its most important care consideration is its grazing habit: this is a plant-shredder, and heavily planted tanks — especially those with soft-leaved species — will be steadily stripped or destroyed. Keepers who want live plants alongside this fish should choose tough, unpalatable species (Anubias, Java fern, Vallisneria) or accept a hardscape-only aquascape of driftwood and rock.
Diet should be vegetable-forward — spirulina flakes/pellets and blanched vegetables as the staple, with occasional protein as a supplement — both to keep the fish healthy and to reduce its tendency to redirect grazing onto plants or fin material when underfed on greens. It is not an aggressive or predatory fish and can be kept with similarly sized, non-nippy community tankmates, though as with many riverine characins it likely does best in a modest group rather than alone; the cache does not document specific shoaling requirements for this species. Because it has essentially never been captive-bred, all stock is wild-collected, which is worth factoring into sourcing decisions.
Conservation
The IUCN Red List assesses Distichodus notospilus as Least Concern, reflecting its wide distribution across multiple coastal river basins from Cameroon to Angola and into the Congo basin, and the absence of evidence for significant population decline. FishBase and the IUCN assessment (dated 2009) concur that the species is not currently threatened.
As with many Lower Guinea and Congo-basin fish, the broader watch items are indirect: habitat pressure from deforestation, sedimentation and damming across its West and Central African river range are long-term concerns for the region's freshwater fish generally, even though this particular species is not flagged as declining. Because the aquarium trade relies entirely on wild-collected specimens for this species, sustainable collection practices in its native range are relevant to its long-term status, though no specific trade-pressure data is available in current sources.