Taxonomy & naming
Labidochromis sp. "Chisumulae Mbweca" has no authority, no year of description, and no FishBase entry. It circulates under the informal field name "chisumulae mbweca," combining a reference to the described Labidochromis chisumulae with a second locality or population tag, "mbweca." Labidochromis chisumulae was described by Digby Lewis in 1982 and is known only from Chizumulu Island in east-central Lake Malawi, one of the more sharply circumscribed ranges in a lake full of narrow-range rock endemics. The "mbweca" form is recognised as occurring nearby and closely resembling true chisumulae, differing in one documented respect: males of the described species carry a broad black band along the lower edge of the dorsal fin that "mbweca" males lack, while females of the two forms are effectively indistinguishable. That single, specific difference is real and documented, but it has never been formalised into a taxonomic description, so "Chisumulae Mbweca" — recorded here at Tumbi Point on the Mozambican shore — remains an undescribed population rather than a confirmed population of Labidochromis chisumulae.
Morphology
Labidochromis chisumulae is a small mbuna even by genus standards, with FishBase recording a maximum of 2.5 in standard length and Konings giving males to about 3 in and females to about 2.5 in total length in the field. A dominant, breeding male of the described species turns a clean sky-blue over much of the body and fins, marked by a dark band running from the eye forward to the mouth and around the lower jaw, dark barring on the flanks, and — the character that separates it from "mbweca" — a broad black band along the lower edge of the dorsal fin. "Mbweca" males are reported to lack that dorsal-fin band while otherwise sharing the same blue body and facial markings; females of both forms are a plain creamy pearl-white and are not reliably distinguishable from one another. Beyond that one documented difference, no further published description isolates "Chisumulae Mbweca" from its close relative.
Habitat
This form is recorded from Tumbi Point, on the Mozambican shore of Lake Malawi, in the general area where the closely related, formally described Labidochromis chisumulae occurs on Chizumulu Island. The described species lives in the sediment-rich intermediate zone where rock gives way to sand, always associated with rocks, at depths of roughly 10–66 ft. No depth or micro-habitat figure specific to the Tumbi Point "mbweca" population has been separately published, so the range given here reflects the closely related described species' documented envelope. Water conditions follow Lake Malawi's typical hard, alkaline inshore chemistry.
Feeding
Labidochromis chisumulae is a picker rather than a rasper: it works the aufwuchs coating submerged rock using slender, forceps-like teeth to pluck small invertebrates — micro-crustaceans, aquatic insect larvae, and other tiny animals — from crevices in the algal mat, rather than biting the algal film itself. No feeding study exists for the "mbweca" population at Tumbi Point specifically, so its diet is presented here as the same invertebrate-picking pattern documented for its close relative, not a separately confirmed fact for this exact form.
Mating
Male Labidochromis chisumulae are not strongly territorial in the conventional mbuna sense: Konings notes that males do not hold and defend a fixed breeding territory, though a male will chase conspecifics away from a favoured feeding site, and the species does not form schools. A conditioned male intensifies into his blue, dark-faced breeding colours and courts passing females wherever he encounters them rather than luring them to a built nest, a relatively loose social structure that gives the species a reputation as one of the more peaceable mbuna. Whether "Chisumulae Mbweca" follows this same pattern precisely has not been separately documented, though there is no reason to expect it to differ given how closely the two forms otherwise resemble each other.
Breeding
Like all mbuna, Labidochromis chisumulae is a maternal mouthbrooder, and "Chisumulae Mbweca" is presumed to follow the same pattern. In the described species, clutches are small — keepers report broods on the order of roughly a dozen up to around twenty-five fry — with the female carrying the developing young for about three weeks before releasing free-swimming fry that are comparatively large and grow quickly. No brood data specific to the Tumbi Point population have been separately published; the figures above are offered as complex-typical context.
In the aquarium
Labidochromis sp. "Chisumulae Mbweca" is an uncommon, specialist find; even the formally described Labidochromis chisumulae is a rarer hobby fish than the ubiquitous Electric Yellow, and this closely related but undescribed Mozambican population circulates, if at all, through specialist collectors rather than general fish shops. A keeper who did obtain it should follow the same template as its described relative: stacked rockwork with caves and overhangs over a strip of open sand, hard alkaline water at roughly pH 7.8-8.6 and 75–82 °F, and a spirulina-based diet supplemented sparingly with frozen invertebrate foods to avoid the risk of Malawi bloat common across mbuna. Males do not defend large territories, making the fish generally peaceable with similarly tempered tankmates, though it should not be housed with more aggressive mbuna such as Melanochromis or large Metriaclima.
Conservation
Labidochromis sp. "Chisumulae Mbweca" has no IUCN Red List assessment, since formal evaluation requires a validly published scientific name and none exists for this form. Labidochromis chisumulae itself is assessed Least Concern, but that status describes a single-island endemic on Chizumulu and cannot be extended to this separate, geographically distinct Mozambican population. As a rock-associated cichlid apparently restricted to Tumbi Point, it shares the general exposures documented across Lake Malawi's narrow-range rock endemics — localised sedimentation, habitat disturbance, and ornamental collecting — but no population-specific data exist to characterise its status further.