Taxonomy & naming
Aulonocara sp. "Deep" is not a formally described species. It has no binomial scientific name, no describing author, no year of publication, and no entry in Eschmeyer's Catalog of Fishes, because no taxonomist has yet published a description of it. It is an informal taxon recorded in the field and survey literature on Lake Malawi's cichlids, including on the malawi.si species database — where it is documented from Nkhata Bay — and it appears under the working name "Aulonocara sp. deep" in published trawl-survey work on the lake's demersal (bottom-dwelling) fish communities. The placeholder name follows the standard convention for undescribed Malawi cichlids: the genus Aulonocara, the abbreviation "sp.", and an informal descriptive tag in quotation marks — here simply "Deep," recording the fish's deepwater habit. It is placed within Aulonocara on the strength of the genus's diagnostic enlarged cephalic sensory pores, the widened lateral-line canals of the head that define the peacocks. Because it is sparsely documented and seldom observed, much of its biology is poorly known, and until a formal description is published no authority or date should ever be attached to it. It should not be confused with the unrelated fish long sold in the hobby as the "Deep Water Hap," which is Placidochromis electra, a different genus entirely.
Morphology
Aulonocara sp. "Deep" is built on the genus's standard plan — a moderately deep, laterally compressed haplochromine body and a head carrying the enlarged sensory pores that define all Aulonocara, the widened lateral-line canals these fish use to detect prey buried in the sand. Detailed morphometric data for this form have not been published, and its precise adult size is not well documented; it sits within the size range typical of the lake's medium-sized peacocks. As a deepwater fish living in low light, it would be expected, like other deep peacocks, to show somewhat restrained coloration compared with the vivid shallow-water forms, though fine details of its colour pattern and of any sexual dimorphism have not been formally recorded. By analogy with the rest of the genus, sexual dichromatism is present, with males more strongly coloured than females.
Habitat
As its name states, Aulonocara sp. "Deep" is a deepwater fish. It is documented from off Nkhata Bay, on the northwestern shore of Lake Malawi, where it occurs below the depths reached by snorkellers and inshore divers — in the dim, cooler, more stable waters of the lake's deeper zones. Lake Malawi stratifies strongly, with a warm, oxygenated upper layer over deeper water that is cooler and, below the oxygen limit, uninhabitable; deepwater fish like this peacock occupy the lower part of the habitable column, above that limit. Published surveys of the lake's trawlable demersal zones — the deeper, bottom-dwelling fish communities sampled by research trawls rather than by divers — record "Aulonocara sp. deep" among the cichlids of those depths, which is consistent with a fish of the open deep rather than the inshore reefs. The water is the warm, hard, strongly alkaline medium of Lake Malawi, cooler at depth than at the surface.
Feeding
Aulonocara sp. "Deep" carries the enlarged cephalic sensory pores that define the peacock genus — the widened lateral-line canals used to detect the faint movements of invertebrates buried in the sand — and so is, by anatomy, a sand-sifting invertivore in the genus mould. In a deep, low-light habitat this sensory mode is especially valuable: a fish that hunts by feeling the substrate through its head pores is far less dependent on light than a visual predator, which suits a life below the bright surface zone. The expected foraging pattern is the genus's hover-and-sift — a motionless pause above the sand, then a darting dip to take a mouthful of substrate and sift out the buried prey. The diet itself is the genus-typical menu of small benthic invertebrates. As with much of this form's biology, however, its feeding has not been directly documented in the wild, and this account rests on its anatomy and its membership in the peacock radiation.
Mating
The social and mating behaviour of Aulonocara sp. "Deep" is essentially undocumented, a direct consequence of how difficult its deepwater habitat is to observe. No courtship, territoriality, or lek structure has been described for it in the wild. By analogy with the rest of the genus it would be expected to be polygynous and lek-like, with no pair bond and with colour-holding males visited by ripe females — the standard haplochromine arrangement — but none of this has been observed and recorded for this particular form. Deepwater Malawi cichlids are among the least-studied fish in the lake precisely because divers cannot easily reach them, and this peacock is one of the resulting blanks.
Breeding
Like all Lake Malawi haplochromines, Aulonocara sp. "Deep" is understood to be a maternal mouthbrooder, in which the female takes the eggs into her mouth immediately after laying and broods them there until the fry are free-swimming, with no male or post-release parental care. Beyond that genus-level certainty, its breeding biology is undocumented: spawning sites, clutch size, and brooding period have never been described for this form, because it lives at depths that make direct observation impractical, and it is not kept in captivity. The reasonable expectation is that it spawns over deep sand in the general peacock manner, but this is an inference from the genus rather than a recorded observation.
In the aquarium
Aulonocara sp. "Deep" is not an aquarium fish. It lives in deep water that puts it beyond the reach of the ornamental collectors who supply the trade, it is sparsely documented even in the scientific literature, and there is no body of husbandry experience for it. A keeper will not find this form offered for sale, and any keeping advice would be pure extrapolation from other deepwater or sand-dwelling Malawi peacocks.
Were a specimen ever to be collected and kept, the general expectation would be a fine sand substrate of at least 2 in for foraging, subdued lighting in keeping with its naturally dim habitat, a footprint of at least 49 in, and water chemistry mirroring Lake Malawi: temperature in the mid-20s Celsius, pH on the alkaline side of neutral (roughly 7.7 to 8.6), and moderately hard to hard general hardness. A single male with several females would be the safest social arrangement, and the standard varied peacock diet — a quality cichlid pellet or flake supplemented with small frozen or live invertebrates, with fatty foods avoided to prevent bloat — would apply. All of this, however, is theoretical; in practice this is a fish of the deep lake that aquarists do not keep.
Conservation
Aulonocara sp. "Deep" has not been evaluated by the IUCN, and as an undescribed form without a formal scientific name it has no Red List assessment of any kind — no status, no category, no published criteria. Its abundance and full range are poorly known: it is documented from off Nkhata Bay and recorded in trawl surveys of the lake's deeper demersal zones, but its true distribution across the deep lake is uncertain. Its deepwater habit places it beyond the reach of the aquarium trade, so it faces no collection pressure, though the lake's deepwater fish communities are subject to commercial trawling and the broader environmental pressures on Lake Malawi. The honest position is simply that it is unassessed and poorly known, and that no fabricated conservation status should ever be attached to it.