Taxonomy & naming
Henochilus wheatlandii was described by the American ichthyologist Samuel Garman in 1890, and it remains the sole recognised species in the monotypic genus Henochilus. Its family placement has shifted with the broader reorganisation of Neotropical characins; older literature and some databases list it under Bryconidae, reflecting its historical grouping near Brycon and its relatives, and the Catalog of Fishes (Eschmeyer, California Academy of Sciences) should be treated as the current authority on its exact family assignment rather than any single source repeated here.
The species has an unusual research history for a described fish: after its 1890 description it was not recorded again for over a hundred years and was widely presumed extinct, until it was rediscovered in the Santo Antônio River in 1996. That rediscovery, combined with its extremely restricted single-river range, is central to why it is treated as a flagship case in Brazilian freshwater fish conservation rather than as a hobby species.
Morphology
Henochilus wheatlandii is a moderately sized, elongate, silvery river characin, with FishBase recording a maximum length of 16.5 in standard length. That is a substantial size for a stream-dwelling characin of this kind — well beyond the scale of a typical small tetra — and it should be read as the real adult size rather than assumed to be a diminutive "minor characin."
Detailed morphological description in the widely accessible literature is sparse; the cached sources for this account focus on its conservation status, distribution and diet rather than fin counts or colour pattern, and this article does not invent specifics beyond what is documented.
Habitat
The species is endemic to the Santo Antônio River, a tributary of the Rio Doce in Minas Gerais, Brazil, and as far as the cited literature records, it is not confirmed elsewhere. It occupies narrow streams with sandy substrate and boulders, in reaches with well-preserved riparian vegetation and dark-coloured water, and both FishBase and the Vieira & Alves (2001) account of threatened fishes note the fast-flowing character of its habitat.
Water chemistry is described as slightly acidic with low nutrient concentrations, consistent with a shaded, structurally intact headwater-to-mid-order stream rather than an open, nutrient-rich lowland river. The 2001 literature on threatened fishes specifically flags this habitat as under active pressure from mining, logging and hydroelectric projects — the same forces that make the species' single-river distribution so precarious.
Feeding
Henochilus wheatlandii is an omnivore: the cached FishBase and Vieira & Alves (2001) sources both record a diet of plant matter and insects, consistent with a stream fish grazing on riparian inputs, algae and invertebrate prey rather than functioning as a predator of other fish. No aquarium-feeding data exists for this species, since it is not established in the hobby, but in the wild it appears to depend on the terrestrial insect fall and plant material that an intact riparian canopy over its home river provides — another reason deforestation along the Santo Antônio is a direct threat rather than an incidental one.
Mating
No courtship or pairing behaviour for Henochilus wheatlandii is documented in the sources available for this account. As a Critically Endangered, single-river endemic with essentially no aquarium or aquaculture history, its reproductive behaviour has not been studied or recorded in the accessible literature, and this account does not speculate beyond that gap.
Breeding
There is no documented breeding record for Henochilus wheatlandii in captivity, and no described spawning mode in the wild in the sources reviewed here. It should not be assumed to follow any particular reproductive strategy — egg-scattering, nest-guarding or otherwise — without direct evidence; the honest state of knowledge is that this species' reproduction is effectively unstudied outside of its confirmed presence and rediscovery in the Santo Antônio River.
In the aquarium
Henochilus wheatlandii has no meaningful presence in the aquarium trade. It is not commercially collected or bred for the hobby, and given its Critically Endangered status and single-river endemism, keeping or trading wild-collected specimens would run directly counter to its conservation. There is no reliable tank-size, water-parameter or tankmate guidance to offer because the species has not been kept in aquaria in any documented way; anyone encountering claims otherwise should treat them with scepticism given how narrow and precarious its known range is.
Conservation
The IUCN Red List currently assesses Henochilus wheatlandii as Near Threatened. The species remains restricted to a single tributary — the Santo Antônio River in the Rio Doce basin, Minas Gerais, Brazil — and was not recorded for more than a century between its 1890 description and its 1996 rediscovery. Vieira & Alves (2001) and subsequent karyotype and biodiversity research on the species have documented pressure on that one river from mining, logging and hydroelectric development.
Because the species is confined to one drainage with no confirmed secondary population, continued habitat degradation, damming or water-quality decline in the Santo Antônio River remains a real long-term concern for a fish with so little geographic buffer. There is no wild-collection trade pressure recorded for this species — its conservation story is almost entirely about habitat, not harvest.