Taxonomy & naming
Pseudotropheus sp. "Red Top Ndumbi" is not a formally described species. It has no scientific name of its own, no describing author, no year of publication, and no entry in Eschmeyer's Catalog of Fishes, because no taxonomist has published a description establishing it. It is an informal taxon recognised in the field and aquarium literature, principally through Ad Konings's documentation of the northern Tanzanian shore. The placeholder name follows the standard convention for undescribed cichlids: the genus Pseudotropheus, the abbreviation "sp." (species), and a descriptive tag, here "Red Top" for its dorsal-fin blaze and "Ndumbi" for its collection locality at Ndumbi Point. "Red top" is not unique to this population or even to this genus — it names a recurring colour pattern independently evolved or maintained in several distinct, unrelated Lake Malawi mbuna lineages around the lake, so the label alone does not imply a close relationship to other "red top" forms elsewhere. Until a revision addresses this population directly it should be treated strictly as a Konings-recognised undescribed form, and no authority or date should be attached to it.
Morphology
Pseudotropheus in its modern sense comprises robust-bodied, moderately elongate mbuna with a blunt head and comb-like unicuspid teeth for algae grazing. Genus-typical adult size runs roughly 3–4.5 in; no formal measurement exists for this population specifically. Consistent with its trade name, breeding males are understood to show a blue body with a vivid orange-to-red blaze across the dorsal fin — the "red top" pattern — though the precise extent and shade of the blaze specific to the Ndumbi population is not documented beyond the name itself. Females and subordinate males are expected to be plainer, in the typical mbuna pattern of duller, more cryptic non-dominant colouration, usually lacking the dorsal blaze.
Habitat
This form is recorded from Ndumbi Point and neighbouring Pombo Rocks, both on the Tanzanian shore in the northern part of Lake Malawi. As with other Pseudotropheus, it is expected to be strictly rock-associated, grazing algal films from rock surfaces in the shallow-to-moderate depths typical of mbuna habitat. The water column here follows the lake-wide profile: warm, alkaline, and well-buffered, broadly mid-20s Celsius with pH on the alkaline side of neutral. As an undescribed, locality-based form its precise depth range and full distribution beyond the Ndumbi–Pombo Rocks stretch of coast are not established.
Feeding
Pseudotropheus as a genus are specialised algae grazers, using comb-like unicuspid teeth arranged in tight rows to scrape algal films and the associated small invertebrates ("Aufwuchs") from rock surfaces in well-lit water. This grazing mode ties the fish to hard, sunlit rock rather than sand or open water, and puts it in direct competition with the dense, mixed mbuna assemblages that share the rock faces at Ndumbi Point and Pombo Rocks. No feeding study exists for this population specifically, but this genus-typical herbivore/detritivore mode is the reasonable characterisation absent contrary data.
Mating
Like other Lake Malawi mbuna, this form is presumed polygynous, with males holding and defending small territories on the rock face, courting passing females from these sites — the bright dorsal blaze likely figuring prominently in the display — while driving off rival males. There is no pair bond. Females move between male territories, choose largely on colour and site quality, and spawn briefly on the rock before departing with the fertilised clutch in the mouth. No behavioural study specific to this undescribed population exists; the account follows the general pattern documented for Pseudotropheus and rock-dwelling mbuna more broadly.
Breeding
Pseudotropheus sp. "Red Top Ndumbi" is a maternal mouthbrooder, as are all Lake Malawi mbuna. After spawning on the rock face, the female carries the fertilised eggs in her mouth for roughly three weeks, feeding little during this period, before releasing free-swimming fry with no further care from either parent. Clutch size has not been documented for this form specifically; by analogy with similarly sized Pseudotropheus species, a modest clutch — likely a few dozen eggs — is a reasonable expectation rather than a measured fact.
In the aquarium
"Red top" mbuna are generally popular in the hobby for their colour contrast, though this specific Ndumbi Point population is a less commonly traded, specialist-import form. Where it is kept, husbandry follows the well-established mbuna template.
Dense, stable rockwork built directly on the tank floor is essential, since this is a strictly rock-associated grazer needing abundant surface area and shelter. A footprint of at least 47 in suits an adult group. Water chemistry should mirror Lake Malawi's profile: temperature in the mid-20s Celsius, pH roughly 7.7–8.6, and well-buffered water, with prolonged soft or acidic conditions avoided. Diet should emphasise vegetable matter — a good spirulina-based flake or pellet as the staple, with algae wafers and blanched vegetables as supplements — reflecting its herbivore/grazer biology; protein-heavy foods should be limited, as herbivorous mbuna are prone to digestive problems on rich diets. As with other mbuna, males are territorial and often aggressive, so a single male with multiple females and adequate rockwork to break sightlines works better than a pair in a small tank. Because "red top" is a widely repeated colour pattern across unrelated Malawi cichlids, keepers should be careful not to mix this Ndumbi population with other, unrelated red-top forms.
Conservation
Pseudotropheus sp. "Red Top Ndumbi" has not been evaluated by the IUCN, and as an undescribed form without a formal scientific name it has no Red List assessment of any kind. That silence is a statement about taxonomy, not about safety. As a rock-restricted population on the northern Tanzanian shore, it faces the general pressures typical of that comparatively less-surveyed coast: ornamental collection and the broader basin-wide stresses of sedimentation and fishing pressure. No conservation status should be fabricated for it. The honest statement is that it is unassessed and that its true range and status remain to be established by formal study.