Taxonomy & naming
Pseudotropheus sp. "Williamsi Makanjila" is undescribed as a distinct taxon: it has no holotype, no authority and no publication year of its own, and no entry separate from P. williamsi in Eschmeyer’s Catalog of Fishes. Pseudotropheus williamsi itself, described by Günther in 1893, is among the very first mbuna formally named and remains a valid species, a deep-bodied, blue-and-black-barred rock-dweller of the southern lake. Field workers and the aquarium trade have long recognised a series of locality-based populations that closely resemble P. williamsi but show minor differences in colour, pattern or proportion — this form is one, distinguished informally by the locality "Makanjila," a point on the lake’s south-eastern shore. Whether it represents a genuinely distinct population or falls within the natural variation of P. williamsi has not been tested by a formal comparative study, and it should be treated as an informally recognised form rather than a confirmed separate taxon.
Morphology
This form follows the general Pseudotropheus williamsi body plan: a deep, robust, laterally compressed mbuna body with the blunt head and thick lips typical of the genus’s algae-scraping species. Reported size is broadly consistent with the complex, roughly 3.5–4.5 in for adults, males somewhat larger. Coloration follows the williamsi pattern of a blue base with dark vertical barring across the flanks, the signature look of the complex, with whatever subtle differences distinguish this population from the nominate form — reported by collectors rather than confirmed in a published comparison — likely involving fine details of bar width, fin edging or overall saturation rather than a fundamentally different body plan. No formal measurements exist for this specific population.
Habitat
Recorded from Ababi Island, Mbenji Island and Penga Penga Island on the Malawian side and from Lumessi and Tumbi Point in Mozambican waters, this form occupies rocky shoreline and island habitat in the south-eastern lake, straddling the international border. The Mbenji Islands group in particular is a well-known site for mbuna diversity, isolated enough from the mainland to support locally distinct populations. Like other Pseudotropheus of the williamsi type, it favours shallow-to-moderate rocky habitat, roughly 7–49 ft, in the lake’s typical warm, alkaline, well-buffered water — around 75–82 °F and pH 7.7–8.6.
Feeding
As a member of the williamsi complex, this form is expected to be a rock-scraping algae grazer, using the genus’s characteristic thick lips and closely packed teeth to comb aufwuchs — algae, diatoms and associated micro-invertebrates — from rock surfaces, the standard mbuna feeding mode. No dietary study specific to this population exists, but its close morphological and ecological resemblance to the well-documented P. williamsi makes this a reliable working description rather than speculation.
Mating
This form is expected to follow the polygynous, lek-like mating system typical of rock-dwelling mbuna, with no pair bond. Males hold and defend a territory on rock, typically centred on a cave or crevice used both for shelter and for attracting females, displaying to passing females rather than pairing exclusively with one. Courtship follows the standard haplochromine pattern of quivering and circling before spawning, which in williamsi-type mbuna generally takes place within or near the male’s cave. Specific behavioural documentation for this named population is not available, so the account here follows the pattern established for P. williamsi and closely related forms.
Breeding
Pseudotropheus sp. "Williamsi Makanjila" is a maternal mouthbrooder, as is every member of its genus. Following spawning, the female takes the fertilised eggs into her mouth and incubates them for roughly three to four weeks, feeding little during this period, before releasing free-swimming fry with no further parental care from either parent. Clutch size has not been documented for this specific population; mbuna of comparable body size in the williamsi complex typically produce clutches in the range of 20–30 eggs.
In the aquarium
Pseudotropheus sp. "Williamsi Makanjila" should be kept as a standard robust rock-dwelling mbuna. Extensive rockwork with caves and crevices is essential, built in a tank of at least 47 in to give territorial males room to establish separate holdings without constant conflict; a sand or fine gravel substrate suits the setup.
Water chemistry should replicate the lake: temperature 75–82 °F, pH 7.7–8.6, and consistently alkaline, well-buffered conditions. Like most Pseudotropheus, it is territorial and best kept with a surplus of females per male and alongside other robust mbuna of similar temperament rather than gentler community fish. Diet should be predominantly vegetable-based, with a spirulina-forward flake or pellet as the staple and high-fat, high-protein foods minimised to reduce the risk of Malawi bloat. Because it closely resembles the described P. williamsi, keepers should preserve accurate locality records to avoid the two being confused or crossed in captivity.
Conservation
No IUCN Red List assessment exists specifically for Pseudotropheus sp. "Williamsi Makanjila"; formally described P. williamsi itself has been assessed by the IUCN, but that assessment does not extend to this informally recognised, potentially distinct population, and no status should be borrowed from the nominate species and applied here without qualification. As a rocky-shore mbuna spanning Malawian and Mozambican waters, it is exposed to the general pressures on the lake’s island-associated cichlid fauna — ornamental collection in particular — but no data specific to this population exist. The accurate statement is that it is unevaluated in its own right.