Taxonomy & naming
Neolebias ansorgii was described by the Belgian-British ichthyologist George Albert Boulenger in 1912. It sits in the family Distichodontidae within the order Characiformes, a family whose better-known members — the genus Distichodus — are considerably larger, deeper-bodied plant grazers; Neolebias represents the small, slender end of the same lineage, alongside the closely related genus Nannaethiops. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) is the governing authority for the valid combination Neolebias ansorgii; no synonymy or generic reassignment is noted here, and the genus placement is retained as given.
The species epithet honours William John Ansorge, a physician and naturalist who collected extensively in West and Central Africa in the early twentieth century, a common dedication among fish described from his collections during that period.
Morphology
Neolebias ansorgii is a small, elongate, laterally compressed characin. Sources differ modestly on maximum size — FishBase records 1 in SL, while the aquarium-focused reference Seriously Fish gives 1.5 in SL as the more commonly cited adult figure — but either way this is a genuinely tiny fish, among the smallest characins kept in the hobby. The body is slender rather than deep, with a small terminal mouth and unremarkable, softly rounded fins typical of small marsh-dwelling characins, lacking the enlarged jaws or heavy scales of its bigger Distichodontidae relatives.
Colouration is subtle: the body carries a fine, often reddish-to-olive sheen along the flanks with a narrow dark lateral stripe, and fins can flush with light red or orange tones, particularly in well-conditioned males. It is not a showy fish by tetra standards, but its coloration intensifies with good water and diet, a common pattern in small blackwater and marsh characins.
Habitat
Neolebias ansorgii is native to Central and West Africa, with records spanning the Congo basin, Nigeria, Cameroon, Gabon and Benin. Within that range it occupies marshes, small vegetated ponds and slow, densely planted creeks rather than open river channels — still, shallow, plant-choked water is the consistent theme across its distribution.
Water in these habitats is warm and soft-to-acidic, consistent with the broader pattern for small West and Central African forest and marsh characins. Seriously Fish gives a temperature range of 75–82 °F and a pH of 5.0–6.0 for the species, figures at the softer, more acidic end of what is typical for warm African river and marsh systems; dense vegetation and low water movement are a consistent habitat feature alongside that chemistry.
Feeding
Neolebias ansorgii is an omnivore, and Seriously Fish notes it does best on live and frozen foods — items such as small daphnia, artemia and other suitably sized live or frozen fare — though it will accept quality dried foods once settled. This preference for meaty micro-foods sets it apart from its plant-grazing Distichodus relatives; there is no indication in the available sources that this species browses algae or plant matter in the way larger Distichodontidae do.
In the aquarium, a varied diet of small live or frozen foods supplemented with good-quality flake or micro-pellet is consistent with what the cached sources describe, and is standard practice for small, delicate marsh characins of this size.
Mating
Specific courtship behaviour for Neolebias ansorgii is not well documented in the available sources. What is recorded, via Seriously Fish, concerns the spawning act itself rather than a distinct courtship phase: ripe females scatter roughly 300 eggs in small packets of about 10 over several days among fine-leaved plants, with no described pair-bonding or nest-preparation behaviour beyond seeking out suitable vegetation.
No reliable external sexual dimorphism is documented in the cached sources for this species; data is sparse here and no colour or fin difference between the sexes should be assumed without further confirmation.
Breeding
Neolebias ansorgii is an egg-scattering species, and Seriously Fish notes it is rarely bred in the aquarium — a fact worth stating plainly rather than glossing over. Ripe females release eggs in small packets of around 10, distributed among fine-leaved plants over the course of several days, with no nest construction and no described parental care; this is consistent with the broader pattern among African Distichodontidae characins, where egg-scattering without guarding is the norm and the family as a whole is not easy to breed at home.
Where spawnings have been achieved, eggs are reported to hatch within about 24 hours at an elevated temperature near 86 °F, with fry becoming free-swimming after a further two to three days. Newly free-swimming fry require infusoria-sized foods initially, moving on to brine shrimp nauplii during their first week. Given how rarely this species is bred, most aquarium stock should be assumed to be wild-collected or line-bred by specialist keepers rather than routinely captive-produced.
In the aquarium
At an adult size of around 1.5 in, Neolebias ansorgii is a genuine nano-tank fish and should be sized and stocked accordingly — a small, densely planted aquarium with soft, acidic water (Seriously Fish gives 75–82 °F and pH 5.0–6.0) and gentle flow suits it far better than a general community setup. As a small, unassuming shoaling characin it should be kept in a proper group rather than singly or in pairs, both for its own security and to see any natural colour and behaviour.
Dense fine-leaved planting is worth emphasising twice over: it mimics the marsh and creek vegetation the species is drawn to in the wild, and it doubles as spawning substrate if a breeding attempt is made. Tankmates should be equally small and peaceful — this is not a fish that can hold its own with typical community tetras or barbs, let alone anything resembling the larger, more robust Distichodus or citharinid grazers found elsewhere in its family. Diet should lean toward small live and frozen foods, with dried foods as a supplement rather than a mainstay.
Conservation
Neolebias ansorgii has not been formally assessed by the IUCN Red List and is classified as Not Evaluated. This is common among small, geographically dispersed African marsh and creek characins that attract little targeted survey effort despite a fairly wide recorded distribution across the Congo basin, Nigeria, Cameroon, Gabon and Benin.
No specific threat data is available in the cached sources for this species. As with many small wetland-associated fishes across Central and West Africa, habitat degradation from wetland drainage and agricultural conversion is a plausible general pressure on marsh-dwelling characins in the region, but this is not something documented specifically for N. ansorgii here and should not be overstated without a formal assessment.