Taxonomy & naming
Diplotaxodon sp. "Macrops North" has no authority, no year of description, and no FishBase entry. It is known only by this informal field name, built from the genus, "sp.", and a tag combining a reference to the described Diplotaxodon macrops with the general area it was collected, the northern lake around Nkhata Bay. That naming pattern matters here because Diplotaxodon macrops is not taxonomically simple: population-genetic work on the wider macrops complex has identified at least three genetically distinct, reproductively isolated lineages — informally called "macrops offshore," "macrops black dorsal," and "macrops ngulube" in the scientific literature — that look nearly identical in the hand and are told apart mainly by subtle differences in male breeding-dress markings. "Macrops North" is a geographically, rather than colour-defined, population within that same unresolved picture. Whether it corresponds to one of those genetically documented lineages, or represents a further, undescribed one, has not been established, and it should not be assumed identical to Diplotaxodon macrops as formally described from the southern lake.
Morphology
Diplotaxodon macrops is a small fish for the genus, with a documented maximum of about 5 in standard length and first maturity around 4.5 in, built on the standard Diplotaxodon plan: an elongate, fusiform, laterally compressed body suited to sustained open-water swimming. Its defining feature is a notably large eye — horizontal eye diameter runs roughly 35–38% of head length, the highest proportion recorded in the genus — an adaptation for gathering the scarce, blue-shifted light of the deep water it inhabits. Out of breeding dress the fish is plainly silvery and countershaded; ripe males of the described species turn dark, almost black, with a white margin along the dorsal fin, a pattern shown to function as a species-recognition signal in the colour-poor twilight zone. No description specific to the northern Nkhata Bay population has been published, so its exact size and the details of its male breeding pattern are not asserted here as documented fact.
Habitat
This form is recorded off Nkhata Bay, on the Malawian shore in the northern half of Lake Malawi. Diplotaxodon macrops as described is a benthopelagic species of the lake's deep shelf, recorded between roughly 76 and 420 ft, with the wider macrops complex documented from about 328–722 ft and peak abundance recorded near 722 ft — well within what researchers call the lake's twilight zone, where light is reduced to a narrow blue band and the lake's permanent anoxic bottom water sets a hard lower limit on habitable depth. No depth record specific to this northern population has been published, so the range given here reflects the complex-typical envelope documented for macrops elsewhere in the lake rather than a confirmed figure for Nkhata Bay. Surface water above this depth follows Lake Malawi's usual warm, hard, alkaline signature, though light and dissolved oxygen, not hardness, are what actually define this genus's world.
Feeding
Diplotaxodon macrops is a zooplanktivore, taking insect larvae — including the phantom midge Chaoborus, abundant in offshore water — small crustaceans, and diatoms, consistent with a low trophic position typical of the genus. Offshore Diplotaxodon as a group are ecologically dominant rather than marginal: a two-year trawl survey of Lake Malawi's pelagic zone found cichlids made up roughly 88% of offshore fish biomass, with two zooplanktivorous Diplotaxodon species alone accounting for about 71% of it. No feeding study exists for the Nkhata Bay northern population specifically, so its diet is presented here as complex-typical zooplanktivory.
Mating
In the blue-only light of the twilight zone, bright nuptial colour cannot function as a species-recognition signal, so Diplotaxodon males instead advertise using monochromatic black, white, and silver patterning — in described macrops, a dark body with a white dorsal-fin margin. Studies of sympatric, closely related Diplotaxodon forms sampled between roughly 40 and 656 ft found that even populations overlapping in space remain reproductively isolated by these pattern differences alone, a striking example of sexual selection operating without colour. Whether "Macrops North" carries a distinct breeding-dress pattern of its own, and how its courtship and spawning specifically play out, has not been documented.
Breeding
As with other Diplotaxodon, this form is presumed to be a maternal mouthbrooder. Fecundity in the genus is notably low for such abundant fish: brooding females of well-studied species are typically found carrying only one or two well-developed fry rather than the larger clutches of small young typical of rock-dwelling mbuna, and offshore surveys suggest organised, seasonal rather than year-round breeding cycles based on gonad activity. No breeding data specific to the Nkhata Bay northern population have been published; the pattern above is offered as complex-typical rather than a documented fact for this form.
In the aquarium
Diplotaxodon sp. "Macrops North" is not an aquarium fish. The macrops complex as a whole is taken almost exclusively by commercial or research trawl from deep, cool, dim offshore water and is essentially absent from the ornamental trade; hobbyists who have encountered any pelagic Diplotaxodon describe it as a rare curiosity rather than a stocked species. A fish built for open, dim, cool water with a large light-gathering eye has little in common with the bright rock-dwelling cichlids that dominate the Malawi hobby, and no husbandry record exists for this specific northern population. It is best appreciated as part of the lake's deep-water community rather than considered for a tank.
Conservation
Diplotaxodon sp. "Macrops North" has no IUCN Red List assessment, since a valid scientific name is required before formal evaluation and none has been published for this form. Diplotaxodon macrops as formally described is assessed Least Concern, reflecting its lake-wide range and the absence of ornamental-trade pressure, but that status describes the type population and cannot be extended automatically to a geographically distinct, taxonomically unresolved northern form. The wider offshore Diplotaxodon community faces pressure from the mid-water trawl fishery and from warming-driven strengthening of the lake's permanent stratification, which reduces the deep mixing that resupplies nutrients and oxygen to the productive water this genus depends on. No population-specific data exist for the Nkhata Bay northern form to say more than that it shares those general exposures.