Taxonomy & naming
The species was described by the British ichthyologist Ethelwynn Trewavas in 1935, in her landmark survey "A synopsis of the cichlid fishes of Lake Nyasa" (Annals and Magazine of Natural History, series 10, volume 16), as Trematocranus auditor. Eschmeyer's Catalog of Fishes records the original material as syntypes in the Natural History Museum, London, under register BMNH 1935.6.14.2238, with the type locality given simply as Vua, on the northwestern shore of Lake Malawi (then Lake Nyasa). Trewavas placed it in Trematocranus, a genus she was using broadly for sand- and intermediate-zone haplochromines; the modern arrangement moves it to Aulonocara Regan, 1922, the lake's "peacock" genus, and that combination has been followed by Eccles & Trewavas in their 1989 reclassification of the Malawi haplochromines, by Maréchal in the 1991 CLOFFA check-list, and by Ad Konings through 2016. Because the genus changed, the authority is written with parentheses: Aulonocara auditor (Trewavas, 1935).
The placement is not entirely settled, however, and the doubt goes back further than any modern database flag. Eccles (1989) had already singled out Aulonocara auditor as one of three species whose generic placement was unclear, and Konings' own closer examination of the holotype — a mature female of 3 in standard length, the only specimen ever collected — reinforced that doubt rather than resolving it. Sand-dwelling Aulonocara have grossly enlarged infraorbital sensory-canal bones that leave the cheek scaleless or covered by only a single row of scales; A. auditor instead carries three ordinary rows of cheek scales and tricuspid teeth in the inner rows, and it shows an indistinct pattern of three series of spots along the flank and at the base of the dorsal fin that Konings likened to Protomelas rather than to any Aulonocara. Pending live material, he provisionally grouped it with the lake's rock-dwelling peacocks rather than the sand-dwellers — a placement that cuts against the sand-dwelling assumption its probable beach-seine collection would otherwise suggest, and which is why Konings, on the malawi.si database, still flags its membership in the genus as uncertain rather than secure.
There is a second, important tangle of names here. In a 1996 Cichlid Room Companion account, Konings reported finding "Aulonocara auditor" alive at Ngara and Mdoka in the far north and described its behaviour in some detail; he subsequently recognised those fish as a distinct species, which he named Aulonocara aquilonium Konings, 1995. The upshot, as malawi.si now states plainly, is that true Aulonocara auditor has never been recognised in the field after its original description and has never entered the aquarium trade — material sold or observed under the auditor name has generally been Aulonocara aquilonium. Much of what older literature says about "Aulonocara auditor" biology therefore belongs, strictly, to aquilonium.
Morphology
This is a small peacock. FishBase, following Maréchal (1991), gives a maximum of 3 in standard length — matching the single known specimen, a mature female of 3 in SL — and malawi.si puts typical adults at around 4 in total length. Beyond size, almost everything that can be said about the living fish is provisional, because the description rests on so little material. The holotype shows the laterally compressed haplochromine body of the genus and an indistinct pigmentation pattern of three series of spots along the flank and at the base of the dorsal fin, which Konings described as more reminiscent of Protomelas than of any typical Aulonocara. Diagnostically it is separated from the superficially similar Aulonocara stuartgranti by its tricuspid inner teeth and by having three ordinary rows of scales on the cheek — rather than the scaleless or single-scale-row cheek produced by the grossly enlarged infraorbital sensory-canal bones of the true sand-dwelling Aulonocara. That absence of sand-dweller pore enlargement, together with the Protomelas-like spotting, is why Konings provisionally grouped the species with the lake's rock-dwelling peacocks rather than the sand-dwellers. The epithet itself points to the one feature Trewavas singled out: a slightly swollen otic (ear) region, reflecting the enlarged cephalic sensory canals that define the peacocks. No information exists on sexual dimorphism — no breeding-coloured male of the genuine species has ever been documented — so the bright nuptial dress typical of male Aulonocara is, for this species, simply unknown. (The often-cited account of a long, straight-snouted northern peacock with shy, schooling habits describes the fish now called Aulonocara aquilonium, not the Vua holotype.)
Habitat
Aulonocara auditor is endemic to Lake Malawi and, on the strict modern reading, is known only from the type locality of Vua, a stretch of the lake's far northwestern shore. The IUCN assessment treats the species as confined to that single point, giving an estimated area of occupancy of just 2 mi² — a figure that reflects the absence of records rather than a measured range. The original specimen was almost certainly taken by beach seine, the dominant inshore fishing method along these shores, which is the basis malawi.si and earlier accounts use for presuming a shallow, sandy biotope; the far-northwestern coast around Vua and Ngara is indeed largely sandy and swampy, with only scattered rock. But the fish's own morphology cuts the other way: its ordinary, unenlarged cheek scales and Protomelas-like flank spotting argue against membership in the sand-dwelling Aulonocara group (see Taxonomy & naming), which is why Konings provisionally placed it with the rock-dwelling peacocks instead, pending live specimens. In situ water chemistry for this exact spot has not been published, but it falls within Lake Malawi's well-characterised surface envelope — warm, hard and strongly alkaline, with temperatures broadly in the mid-20s Celsius and a pH around 7.7 to 8.6 across the upper water column. FishBase classifies the species as benthopelagic and freshwater, in the tropical band between roughly 10 and 11 degrees south. The honest position is that the species' true habitat, depth band, and even its basic ecological guild within the genus remain undocumented and, on present morphological evidence, genuinely uncertain.
Feeding
No direct dietary study of Aulonocara auditor exists; its trophic biology is inferred, cautiously, from the genus. Aulonocara peacocks are typically sand-sifting invertivores whose hallmark is a battery of greatly enlarged sensory pores on the head: the fish hovers motionless just above open sand, detects the faint movements of invertebrates buried in the substrate through these lateral-line pits, then strikes down and takes a mouthful of sand, sorting out prey and expelling the spent grains. FishBase records the diet for this species, after that genus-typical pattern, as small invertebrates living in the sand, and places it near trophic level 3.5 — but this figure should be read with real caution. The holotype lacks the enlarged, scale-displacing infraorbital sensory-canal bones that mark the true sand-dwelling Aulonocara, and Konings, on that evidence together with its Protomelas-like flank spotting, provisionally placed it among the rock-dwelling peacocks instead. If that placement holds, the classic sand-hovering, pore-detection feeding style may not describe this species at all, and its actual diet and foraging mode remain genuinely open questions. Whether its tricuspid inner teeth hint at a slightly different prey or processing style is likewise unknown, because the feeding behaviour described in the field literature under the auditor name actually pertains to the unrelated case of Aulonocara aquilonium.
Mating
Nothing has been observed of courtship, social structure or territoriality in the true Aulonocara auditor. The behavioural account that circulates under this name — territorial males holding loosely defended stations on sand between rocks at about 66 ft depth, large foraging schools of females, and a tolerant, low-aggression demeanour reminiscent of the "Chitande type" peacocks — comes from Konings's 1996 observations of fish at Ngara and Mdoka that are now assigned to Aulonocara aquilonium. By analogy with the genus, Aulonocara auditor is expected to be a polygynous, lek-type breeder with no pair bond, in which colourful males defend small spawning territories that females visit, but this is inference from its relatives rather than anything recorded for the species itself.
Breeding
Breeding in Aulonocara auditor has never been documented. Every member of the genus for which reproduction is known is a maternal (ovophilous) mouthbrooder: the female lays a small clutch, takes the eggs immediately into her mouth, and is induced to collect milt from the male — drawn to the egg-spot markings on his anal fin — fertilising the clutch already in her buccal cavity. She then broods the developing eggs and larvae in her mouth for roughly three to four weeks, fasting through much of that period, before releasing free-swimming fry, with no further parental care and no male involvement after spawning. Clutches in peacocks of this small size class are modest, typically on the order of a few dozen eggs. All of this is the confident genus-typical pattern and is the best available expectation for Aulonocara auditor, but it should be read as inference: no spawning, clutch or brooding observation exists for the species as strictly defined.
In the aquarium
A word of caution before anything else: what has historically circulated in the trade and in hobbyist literature as Aulonocara auditor is almost certainly Aulonocara aquilonium — the northern peacock Konings redescribed once he realised the two were different fish. The genuine Aulonocara auditor has never been reliably collected alive, never photographed in the wild, and has not entered the trade. A keeper who is sold "Aulonocara auditor" should understand they are almost certainly keeping Aulonocara aquilonium, or possibly another undetermined northern peacock; the husbandry notes here follow the Aulonocara peacock pattern and are the best honest guidance available.
For a peacock of this size class — around 4 in total length for an adult — a standard recommendation in the hobby is a tank of at least 47 in (roughly 80 US gal), though a more generous footprint of 59 in or more is preferable, both for the swimming room the fish uses and for the harem arrangement that peacocks require. The hardscape should consist of a layer of fine white or light-coloured sand several centimetres deep — sand is functional, not decorative, because peacocks feed by hovering over it and detecting buried invertebrates through their lateral-line pits — with substantial rockwork toward the back and ends of the tank to provide sight breaks. Open sandy areas in the foreground are where the male will spend most of his time, so they should be preserved rather than filled with decoration.
Water chemistry must match Lake Malawi's: temperature 75–81 °F, pH 7.8–8.5, and hard, well-buffered alkaline water (general hardness 10–20 °dH is typical in Malawi-biotype tanks). Filtration should be robust — overstocking in cichlid communities puts heavy bioload on a system — and good oxygenation matters. Soft or acidic water will stress these fish and suppress colour and breeding behaviour over time.
Social arrangement follows the peacock standard: one male per harem of three or more females. Males are polygynous and do not form pair bonds; a single male with one female leads to harassment and physical damage of the female, particularly when she is brooding. Females are maternal mouthbrooders — by analogy with the genus — who carry eggs and early larvae in the buccal cavity for roughly three weeks before releasing free-swimming fry. A brooding female should ideally be moved to a separate holding tank or at least a well-structured tank with refuges, because other fish will pursue and stress her. The male takes no role in brooding and should not be housed in the same small space as a mouthbrooding female.
Tankmate selection requires care. Other Lake Malawi cichlids that share the peacock's soft temperament — non-aggressive Haplochromis-group fish of broadly similar size — can work, but mixing male Aulonocara of very similar colour or form invites hybridisation, which is a serious and common problem in the hobby. Males will sometimes court and spawn with females of related peacock species, producing hybrids that can look superficially like a genuine species; keeping only one Aulonocara taxon per tank, or ensuring males are visually very distinct from one another, is the standard safeguard. Boisterous and aggressive mbuna (rock-dwelling Lake Malawi cichlids) are generally unsuitable companions — they will outcompete and bully peacocks, particularly at feeding and during the male's territorial displays. Larger, predatory haplochromines are obvious risks. Peaceful open-water schooling fish can sometimes share a large Malawi community tank, but should be chosen with the alkaline, hard water requirements in mind.
Conservation
The IUCN Red List assessed Aulonocara auditor as Data Deficient on 22 June 2018 (assessor Ad Konings; reviewer Jos Snoeks), a change from its 2006 listing of Vulnerable. The justification is candid: the species is known only from a single specimen collected at Vua, has never been relocated, and there is no information on its population, ecology, use or threats — too little, in short, to judge its risk of extinction. The assessment notes one plausible concern: if it is, as suspected, a sand-dwelling fish, it could be exposed to — or may already have been extirpated by — intensive beach seining along the northwestern shore. It carries no CITES listing and, because it is effectively absent from the trade, no collection pressure of its own. That species-level uncertainty sits inside a lake under real and worsening strain. Lake Malawi supports one of the planet's richest freshwater fish faunas, on the order of 800-plus cichlid species, and a basin-scale review by Chavula and colleagues (2023) documents mounting sediment and nutrient loading, shoreline degradation, warming surface waters and reduced mixing, alongside heavy fishing pressure on inshore stocks. A 2019 IUCN freshwater assessment of the Lake Malawi/Nyasa/Niassa catchment found a substantial fraction of the lake's endemic fishes at elevated extinction risk. For a presumed shallow, sand-associated endemic known from one point on a heavily seined coast, these are precisely the pressures that matter — and the deeper problem is that, without rediscovery and basic field data, we cannot even tell whether Aulonocara auditor still exists.