Taxonomy & naming
Otopharynx sp. "Heterodon Likoma" has no describing author, no publication date, and no entry under a validated name in Eschmeyer's Catalog of Fishes. The trade name follows the standard convention for undescribed cichlids allied to a known species: the genus, a reference to the close described relative Otopharynx heterodon (Trewavas, 1935) — whose species name, Greek for "different teeth," refers to its unusual dentition compared with other Otopharynx — and a locality qualifier, "Likoma," for Likoma Island, where this population is recorded. The genus Otopharynx, raised by Regan in 1920, contains a mix of open-water plankton feeders and more benthic, sediment-associated species; O. heterodon belongs to the latter group, first collected by trawl rather than by diving observation. This Likoma population is treated as a distinct, geographically separate population pending formal study, and no authority or date should be attached to it.
Morphology
Detailed morphometrics specific to this Likoma population have not been published, but its trade name points directly to its most distinctive feature: an elongated snout, shared with its close relative O. heterodon, associated with picking prey from soft, sediment-covered substrate in deep water rather than grazing hard surfaces. The body is expected to follow the moderately elongate, laterally compressed Otopharynx form typical of the genus's more benthic species. Genus-typical size for mid-sized Otopharynx runs to roughly 4.5–6 in total length; no validated maximum has been documented for this specific form. Sexual dichromatism is expected on general Malawi cichlid grounds, with breeding males more strongly and contrastingly coloured than females, though the specific pattern for this population has not been described.
Habitat
The form is recorded from a single point off Likoma Island, a large Malawian island lying out in the open lake, closer to the Mozambican coast than to the Malawian mainland and surrounded largely by deep water. Its close relative O. heterodon is a deep-water species, originally documented from trawl surveys rather than shallow diving observation, and this form is presumed to occupy a broadly similar deep, soft-substrate habitat around the island's drop-offs, well below the depths typically accessible to recreational diving, though the precise depth range for this specific population has not been published. The surrounding water follows the general Lake Malawi profile — warm, alkaline, and well-buffered — though deep-water zones can run cooler and darker than the well-lit shallows for which Likoma's rocky shoreline is better known.
Feeding
Otopharynx heterodon and its close relatives are understood to feed on invertebrates picked from soft, deep-lake sediment, using their elongated snout and unusual dentition to extract prey — likely including molluscs, insect larvae, and other benthic organisms — from within or on top of the substrate rather than by grazing algae from rock. Otopharynx sp. "Heterodon Likoma" is presumed to feed similarly, though no dedicated feeding study has been published for this Likoma population specifically.
Mating
Breeding behaviour has not been documented for this form. By analogy with other benthic, deep-water Otopharynx species, males are expected to establish territories on the lake floor and display to visiting females in breeding colour, following the general haplochromine courtship pattern, though the deep, low-light habitat typical of heterodon-type Otopharynx makes direct field observation difficult, and few detailed accounts exist even for the described relative.
Breeding
As in all Lake Malawi haplochromines, reproduction is understood to be by maternal mouthbrooding: the female carries the fertilised eggs and subsequent fry in her mouth, without normal feeding, for several weeks until they are ready for independent release, with no further parental role for the male. Clutch size and brooding duration have not been documented for this form or, in detail, for its close relative O. heterodon, given how rarely deep-water Otopharynx are observed directly in the field.
In the aquarium
Otopharynx sp. "Heterodon Likoma" is a rare fish in the aquarium trade, reflecting its deep-water habitat and the difficulty of collecting it compared with shallow rocky-shore mbuna, including the very mbuna that make Likoma Island a well-known collection point. A tank should provide a soft sand substrate suited to a species that naturally forages over sediment, along with open swimming space and only modest rockwork, since this is not a cave-dwelling fish. Water chemistry should follow the Lake Malawi standard — alkaline and well-buffered, pH roughly 7.7 to 8.6, temperature 75–82 °F — and, given the species' deep-water origin, a stable, well-filtered environment is advisable. Diet should include sinking pellets and small live or frozen invertebrates, such as bloodworm and mysis shrimp, reflecting its natural benthic-invertebrate diet.
Conservation
Otopharynx sp. "Heterodon Likoma" has not been evaluated by the IUCN and, as an undescribed form, has no Red List status of any kind. Deep-water Lake Malawi cichlids in general are less intensively surveyed than shallow rocky-shore species, simply because they are harder to observe and collect, so both the true range and any potential threats to this form remain poorly known. In the absence of a formal assessment, caution rather than either alarm or reassurance is the appropriate stance.