Taxonomy & naming
Otopharynx sp. "Auromarginatus Jakuta" has no describing author, no publication date, and no entry under a validated name in Eschmeyer's Catalog of Fishes. The trade name follows the standard convention for an undescribed form allied to a known species: the genus, a reference to the described relative Otopharynx auromarginatus (Boulenger, 1908) — the type species of Otopharynx, named for the golden margins of its fins — and "Jakuta," the collection point on Chizumulu Island. Otopharynx auromarginatus is itself a widespread, lake-wide species reaching the upper Shire River, and it has accumulated a number of informal, locality-specific field names describing variation around the lake; Jakuta is the label attached to the Chizumulu Island population. Whether this population differs from typical O. auromarginatus in more than fin colour or minor proportions has not been established by any published study, and it should be treated as an unresolved form pending that work.
Morphology
No morphometric study has been published for this population specifically. Its trade name points to a resemblance to Otopharynx auromarginatus, the large type species of the genus, which reaches about 9.5 in total length and carries the genus's laterally spotted melanic pattern along with the golden fin margins that give the species its name; a notably high gill-raker count (14–18 on the lower outer arch) also distinguishes true auromarginatus from smaller relatives. That figure is used here only as a genus/species-typical reference rather than a direct measurement of the Jakuta population. Sexual dichromatism is expected on general Malawi cichlid grounds, with breeding males more strongly coloured than females, though the specific pattern at Chizumulu Island has not been documented.
Habitat
Otopharynx sp. "Auromarginatus Jakuta" is recorded from Chizumulu Island, a small island rising from open water in the northern-central part of Lake Malawi, well known among Malawi cichlid enthusiasts for the locally distinct populations found around its shoreline. Otopharynx auromarginatus, the described relative this form is named after, is a sand-dwelling species that schools over open sandy bottom at around 33 ft depth, and the Jakuta population is presumed to occupy broadly similar sandy habitat fringing the island. The surrounding water follows the general Lake Malawi profile — warm, alkaline and well-buffered — though the precise depth and habitat details specific to this population have not been documented.
Feeding
Otopharynx auromarginatus is an unusually gentle feeder for a Malawi cichlid, grazing phytoplankton and fine organic material from the muddy layer covering open sand rather than hunting invertebrates or fish, a diet reflected in its high gill-raker count. Otopharynx sp. "Auromarginatus Jakuta" is presumed to feed similarly, though no dedicated feeding study has been published for this Chizumulu Island population.
Mating
No courtship behaviour has been documented for this form. By analogy with Otopharynx auromarginatus, which schools over open sand outside of breeding, males in nuptial colour are expected to separate from these schools and establish display sites on the sandy bottom, courting passing females in the polygynous, lek-like manner typical of Lake Malawi's sand-dwelling haplochromines. The specifics of any spawning territory or display arena at Chizumulu Island have not been recorded.
Breeding
As with all Lake Malawi haplochromines, reproduction is presumed to be by maternal mouthbrooding: the female would incubate the fertilised eggs in her buccal cavity for roughly three weeks, fasting throughout, before releasing free-swimming fry, with no further parental role for the male. Being drawn from a larger-growing relative, this population might be expected to produce somewhat larger clutches than small Otopharynx, but no figures have been recorded. The reproductive details given here are inferred from the wider Malawi haplochromine flock rather than measured for this form.
In the aquarium
Otopharynx sp. "Auromarginatus Jakuta" is an uncommon fish in the trade, reaching keepers mainly through specialist Malawi cichlid importers as a locality-labelled form. A tank should provide a fine sand substrate over a generous open footprint, since Otopharynx auromarginatus is a sand-grazing species that needs room to forage, with modest rockwork rather than a dense mbuna-style aquascape. Water chemistry should follow the Lake Malawi standard — alkaline and well-buffered, pH roughly 7.7 to 8.6, temperature in the mid-20s Celsius. Its natural diet of phytoplankton and fine substrate material argues for a vegetable- and aufwuchs-leaning prepared diet rather than a heavily meaty one, avoiding the rich, protein-dense feeds that predispose low-trophic Malawi grazers to digestive problems. As a schooling, comparatively peaceful sand fish, it suits a spacious community of similarly sized Malawi haplochromines.
Conservation
Otopharynx sp. "Auromarginatus Jakuta" has not been evaluated by the IUCN and, as an undescribed form, has no Red List status of any kind. Its described relative, Otopharynx auromarginatus, is assessed as Least Concern lake-wide, but that status does not extend to an island-specific population, which could in principle be affected by localised ornamental collection or habitat disturbance around Chizumulu Island in ways the widespread species is not. No population-specific data exist to assess this. The honest statement is that the Jakuta form is unassessed, and that a form known from a single island locality warrants the same general caution applied to other narrow-range Malawi endemics.