Taxonomy & naming
Tropheops sp. "Macrophthalmus Chitimba" has no formal scientific name, no describing author, and no entry in Eschmeyer's Catalog of Fishes. The trade label combines the specific epithet of the described species Tropheops macrophthalmus — Ahl, 1926, originally as Pseudotropheus macrophthalmus, from the Greek for "large eye" — with the collection site, Chitimba Bay, and a depth qualifier used by collectors to separate it from shallower fish at the same bay. Konings' field notes on T. macrophthalmus itself mention a distinctive "Chitimba Blue" population photographed in the deeper part of the bay, and this form is closely associated with that population or one very like it. Whether Tropheops sp. "Macrophthalmus Chitimba" is properly conspecific with the described T. macrophthalmus, a deep-water ecotype of it, or a separate lineage has not been settled, and it is treated here strictly as an undescribed trade form rather than a synonym of the named species.
Morphology
Body plan follows the genus: compact and laterally compressed, with the steep forehead and blunt, comb-toothed mouth typical of Tropheops grazers. The defining feature carried in the name is eye size — a large eye relative to head length, the same trait that gives the described Tropheops macrophthalmus its epithet. Enlarged eyes are a recurring adaptation among Lake Malawi rock cichlids collected from deeper, dimmer water, where more of the available light needs to be gathered for the fish to forage and interact effectively; a Chitimba Bay population collected specifically from depth fits that pattern. Male colouration has not been documented in enough detail in the sources available here to describe confidently; as in other Tropheops, dominant males are expected to carry the more saturated pattern, with females and non-breeding fish plainer. No independently published, form-specific colour account exists for this population.
Habitat
This form is known only from Chitimba Bay, a sheltered bay on the Malawian shore near the northern end of the lake, and specifically from its deeper water rather than the shallow rock and sand at the bay's margins. Chitimba Bay has produced several distinct locality forms across genera — a pattern typical of the North Malawi coast, where isolated bays and reefs separated by open sand or deep water each accumulate their own mbuna populations. Depth is the key habitat variable for this particular form: it sits in the dimmer, cooler lower reaches of the bay rather than the sunlit shallow rock used by most Tropheops, which is consistent with the enlarged-eye trait in its name. Water conditions otherwise follow the Lake Malawi norm — warm, hard, and strongly alkaline — though the deeper water it occupies runs somewhat cooler and dimmer than the shallow littoral used by most of the genus.
Feeding
Tropheops as a genus are specialised aufwuchs grazers, using dense rows of comb-like teeth to scrape the algae-and-diatom film from sunlit rock. Algal productivity falls off with depth as light becomes limiting, so a population established in the deeper part of Chitimba Bay likely forages on thinner, more shade-tolerant algal turf than shallow-water Tropheops, and may take a proportionally larger share of drifting plankton and detritus when algal growth is sparse — a flexibility documented in other deep-collected Tropheops forms. No feeding study specific to this population has been published, and this account follows the well-established genus pattern rather than direct observation.
Mating
No dedicated behavioural study exists for this form. Tropheops generally follow a territorial, lek-like mating system: dominant males hold and defend small patches of rock, displaying breeding colour to attract passing females, with no pair bond. In deeper-water Tropheops populations, territories are typically more diffuse than in the crowded shallow littoral, simply because there is less competition for space at depth — a pattern reported for other deep-collected mbuna forms, though not documented specifically for this population.
Breeding
As in all Lake Malawi haplochromines, reproduction is by maternal mouthbrooding. After spawning at the male's territory, the female takes the fertilised eggs into her mouth and broods them for roughly three to four weeks before releasing free-swimming fry, with no paternal involvement beyond courtship and fertilisation. Clutch size has not been documented for this specific form; by analogy with similarly sized Tropheops, a modest clutch of a few dozen eggs is a reasonable expectation.
In the aquarium
Tropheops sp. "Macrophthalmus Chitimba" reaches the hobby only occasionally, through specialist importers working the north Malawi coast, and is a fish for an established Tropheops keeper rather than a first mbuna. As with other deep-collected forms, newly imported fish can be sensitive to bright, harsh aquarium lighting; a tank with some shaded rockwork and moderate lighting is a reasonable accommodation, at least while the fish settles.
Water should mirror the lake: hard, alkaline, and stable, with a pH in the high 7s to mid 8s and temperature in the mid-20s Celsius. A rock-dominated aquascape with distinct piles and clear sightlines between them, on a base of fine sand, suits the genus generally. Diet should stay vegetable-forward — a spirulina-based flake or pellet as the staple — since high-protein diets are strongly linked to the digestive disorder hobbyists call Malawi bloat in mbuna. Given how easily Tropheops trade forms are confused, and how little independent documentation exists for this one, keepers intending to preserve a clean line should source only from dealers who can vouch for Chitimba Bay provenance.
Conservation
Tropheops sp. "Macrophthalmus Chitimba" has not been evaluated by the IUCN and, as an undescribed form, carries no Red List status of any kind. Its known range is limited to the deeper water of a single bay, which — if the population is genuinely distinct rather than simply the deep end of a wider-ranging species — would make it a tightly localised endemic and correspondingly vulnerable to concentrated collecting or to habitat disturbance within that one bay. No formal conservation status should be assumed pending taxonomic clarification.