Taxonomy & naming
Placidochromis sp. 'phenochilus gissel' has no describing author, no type specimen, and no listing in Eschmeyer's Catalog of Fishes. Its trade name references the described species Placidochromis phenochilus, whose epithet, built from Greek phainein (to show, appear) and cheilos (lip), points to its most obvious feature: noticeably thickened, hypertrophied lips. This undescribed form is understood by collectors as a closely related field population to that species, with 'Gissel' identifying this particular collection point or form within the wider phenochilus-type group, recorded here from a cluster of reefs near Makanjila in the far southeast of the lake — the same reef cluster that also hosts undescribed forms in other genera, including Mylochromis and Tropheops, documented here from Chiofu, Gome and neighbouring sites.
Morphology
Placidochromis phenochilus-type fish are recognised chiefly by their thickened, fleshy lips, used to extract invertebrates from crevices deep in the rock — a specialised feeding adaptation shared across a handful of similarly lipped Malawi haplochromine species and popularly grouped by hobbyists under names built around 'lips.' A full published description of this specific form's colour pattern or fin shape does not exist, and none is invented here; Placidochromis generally show more subdued dichromatism than mbuna, with males typically a silvery-blue base colour carrying darker markings, and females plainer. Precise measurements — standard length, body depth, fin ray counts — have not been published for this form, and none are estimated here beyond the genus-typical range. As in most Lake Malawi haplochromines, males are expected to be the larger, more strongly coloured sex at maturity.
Habitat
This form is documented from a tight cluster of reefs near Makanjila in the far southeast of Lake Malawi — Border, Chiofu, Gome, Liwani, Masinje and Ntekete — a stretch of shoreline that also supports several other undescribed forms recorded under different genera at the same or adjacent sites. Placidochromis phenochilus-type fish are typically associated with deeper rocky habitat than most mbuna, foraging along crevice-rich rock faces rather than the shallow surge zone favoured by algae-grazing genera. Sand and sand-rock transition habitat in Lake Malawi grades gradually with depth, from shallow, current-swept shoreline to calmer, more stable conditions below the wave-mixed zone. Water chemistry is essentially uniform throughout the lake's oxygenated upper layer — hard and strongly alkaline — so differences between sites are mostly about substrate, rock cover and depth rather than water quality.
Feeding
No feeding study specific to this form exists, but by analogy with described phenochilus-type Placidochromis, it is expected to forage by probing rock crevices with its thickened lips for small invertebrates otherwise inaccessible to fish without this adaptation, a feeding mode distinct from the algae-grazing habits of the mbuna sharing its reefs. Non-mbuna Malawi haplochromines in this size class generally take a more varied, protein-inclusive diet than the strict algae grazers of the rocky shore, reflecting their sand and transition-zone habitat where invertebrate prey is more available than dense algal turf. Feeding behaviour specific to this population has not been documented, and no more precise detail is asserted here.
Mating
Mating behaviour has not been documented for this form specifically. Non-mbuna Malawi haplochromines of this build typically breed with males holding a display site on or among rock, visited by ripe females for courtship and spawning, without the dense lekking aggregations typical of some mbuna. As in mbuna, males of most non-mbuna Malawi haplochromines are expected to carry egg-spot markings on the anal fin that mimic the female's own eggs, prompting her to draw in sperm while collecting the true fertilised eggs into her mouth during spawning — the same egg-dummy fertilisation mechanism that underlies mouthbrooding reproduction across the lake's cichlid radiation, though it has not been confirmed specifically for this form.
Breeding
Reproduction is by maternal mouthbrooding, as in all Placidochromis and the wider Lake Malawi haplochromine radiation. The female takes the fertilised eggs into her mouth after spawning and broods them alone through development, releasing free-swimming fry after several weeks with no further parental care. Clutch size and brooding duration have not been recorded for this form. Comparably sized non-mbuna haplochromines typically produce larger clutches than small mbuna, often several dozen eggs, reflecting their bigger adult body size. A brooding female is expected to feed little or not at all for the several weeks of mouthbrooding and to retreat to less exposed habitat until the fry are released, matching the pattern seen across Lake Malawi's maternal mouthbrooders generally.
In the aquarium
This form is not established in the aquarium trade under this name, and no husbandry account specific to it exists. Were it kept, care would follow the general template for phenochilus-type Placidochromis: a large tank with substantial rockwork offering deep crevices to suit its specialised feeding habit, hard alkaline water matching the lake, and a varied, protein-inclusive diet reflecting its likely invertebrate-based feeding. Were it established in the trade, a stocking approach of one male to multiple females would be standard, following general Malawi haplochromine practice, in a tank sized for its larger adult build relative to mbuna. Weekly partial water changes and stable water chemistry matching the lake matter for any Malawi cichlid, mbuna or otherwise.
Conservation
Placidochromis sp. 'phenochilus gissel' has not been evaluated by the IUCN Red List and, as an undescribed form, is not currently eligible for formal assessment. Its apparent restriction to a single reef cluster near Makanjila carries the general exposure of narrow-range Malawi rock-dwellers to localised ornamental collection and habitat disturbance. Lake Malawi's non-mbuna haplochromines face the same basin-wide pressures as its rock-dwelling mbuna: overfishing of food species, sediment runoff from catchment deforestation, and a warming climate altering thermal stratification and deep-water oxygen levels. Sand-dwelling and transition-zone species can additionally be exposed to bottom-disturbing fishing gear in ways strict rock-dwellers are not.