Taxonomy & naming
Petrotilapia sp. "Likoma Barred" carries no describing author, no publication date, and no entry under a validated name in Eschmeyer's Catalog of Fishes. Its trade name follows the standard undescribed-mbuna convention: genus, plus a descriptive tag for male breeding colour, here a vertically barred pattern, and a locality qualifier distinguishing this Likoma-area population from Petrotilapia forms elsewhere in the lake. The genus Petrotilapia (Regan, 1922), known informally to hobbyists as the "skunks" after the type species P. tridentiger, is defined by robust jaws and broad, closely packed teeth adapted for scraping tough algal turf from wave-washed rock — a diet and dentition distinct from the more delicate feeding of most other mbuna. The genus is also notorious among taxonomists for strong colour polymorphism: several distinct male colour morphs frequently coexist within a single population, which has made species boundaries within Petrotilapia unusually difficult to draw and has left many named forms, including this one, undescribed. No formal study has established whether Likoma Barred represents a distinct species or one colour morph within a broader Petrotilapia population at these reefs.
Morphology
Petrotilapia are among the more robustly built mbuna, with a thick-set head, strong jaws, and closely packed, broad teeth suited to scraping tough algal mats from rock — a heavier dentition than the more slender-toothed grazing mbuna such as Maylandia. As implied by its trade name, breeding males of this form carry a vertically barred colour pattern; the precise ground colour and bar spacing have not been documented in a formal description. Genus-typical size for Petrotilapia runs larger than most mbuna, to roughly 4.5–6 in total length, with males somewhat larger than females. Sexual dichromatism is pronounced throughout the genus, and Petrotilapia is additionally notable for polymorphism among males themselves — multiple colour morphs can coexist at a single site — so "barred" may represent one of several morphs present around Likoma Island rather than the only pattern found there.
Habitat
The form is recorded from reefs around Likoma Island in central Lake Malawi — Likoma Island itself, Ndumbi Rocks, and Taiwanee Reef. Petrotilapia are specialists of wave-exposed, high-energy rocky shoreline, where strong surf keeps algal turf short and vigorous, favouring their robust scraping dentition over the lighter grazing style of other mbuna. They typically hold territories in the shallow-to-moderate rocky zone, generally within the top 33–49 ft, on exposed rock faces rather than in sheltered crevices. The surrounding water is warm, hard, and alkaline, consistent with Lake Malawi's rocky littoral throughout.
Feeding
Petrotilapia are algae specialists adapted to the toughest feeding niche among Lake Malawi's rock-grazing mbuna: their broad, closely set teeth let them scrape and tear dense, wave-hardened algal turf from exposed rock that more delicately toothed mbuna cannot exploit as effectively. Petrotilapia sp. "Likoma Barred" is presumed to feed in this genus-typical manner, defending a feeding territory on exposed rock and grazing algae directly from the surface, though no feeding study specific to this population has been published. This specialisation comes with a trade-off: because Petrotilapia depend on the toughest, most exposed algal turf, they are generally restricted to the most wave-battered parts of the reef and are less able than more generalist mbuna to shift onto sheltered rock when conditions change, a constraint that likely applies to this Likoma-area form as much as to the genus generally.
Mating
Mature males are expected to hold and vigorously defend a feeding-and-breeding territory on exposed rock, a defence that in Petrotilapia is generally more aggressive than in many other mbuna genera given the value of well-exposed, algae-rich rock surfaces. Males display their breeding colour — barred, in this form — to attract passing females, following the standard haplochromine courtship pattern built around egg-spot markings on the anal fin. Given the genus's tendency toward coexisting male colour morphs, more than one Petrotilapia colour type may compete for territory on the same reef around Likoma Island, though the details of that dynamic have not been documented specifically for this form.
Breeding
As in all Lake Malawi haplochromines, reproduction is by maternal mouthbrooding: the female collects the fertilised eggs into her mouth after spawning and carries them, without normal feeding, for several weeks until the fry are developed enough for independent release. The male takes no further role once spawning is complete, offering no protection to the female or the developing brood, and territorial defence of the feeding rock reverts to his usual priority of guarding algal turf rather than mate or offspring. Brooding females generally withdraw from exposed feeding rock into more sheltered parts of the reef for the duration, both to reduce disturbance and to avoid confrontation with territorial males while unable to feed normally. Clutch sizes in Petrotilapia tend toward the larger end for mbuna, reflecting the genus's larger adult body size compared with most other rock-dwelling cichlids, though exact figures for this Likoma-area population have not been documented.
In the aquarium
Petrotilapia sp. "Likoma Barred" would be kept as a robust rock-grazing mbuna: a tank with substantial rockwork offering exposed grazing surfaces as well as retreats, a sand substrate, and strong water movement is beneficial given the species' natural high-energy habitat. Water chemistry should match Lake Malawi's rocky zone — hard and strongly alkaline, pH roughly 7.7 to 8.6, temperature 75–82 °F. Petrotilapia are known for pronounced aggression, often more so than typical mbuna, so generous tank size, careful stocking density, and one male to several females (or a very large, densely decorated mixed-mbuna system) are important to manage conflict. Diet should be strongly vegetable-based — spirulina flake or pellet, with algae wafers welcome — and fatty, protein-heavy foods should be minimised given the risk of digestive bloat common to Malawi mbuna.
Conservation
Petrotilapia sp. "Likoma Barred" has not been evaluated by the IUCN and, as an undescribed form, has no Red List status. Its documented range is limited to reefs around Likoma Island, one of the lake's more intensively collected mbuna hotspots given its accessibility and the density of locally endemic forms found there. That popularity among collectors, combined with a narrow known range, is reason for caution regarding collection pressure, even though no specific threat has been formally documented for this particular colour form. Several formally described Petrotilapia species elsewhere in the lake have been assessed by the IUCN, illustrating that the genus as a whole is not immune to conservation concern despite the apparent local abundance of many of its colour morphs.