Taxonomy & naming
Aulonocara korneliae was described in 1987 by Manfred K. Meyer, Rüdiger Riehl and H. Zetzsche, in a wide-ranging revision of the genus Aulonocara published in Courier Forschungsinstitut Senckenberg (volume 94, pages 7–53). That same paper erected six new species at once — Aulonocara ethelwynnae, Aulonocara hansbaenschi, Aulonocara hueseri, Aulonocara korneliae, Aulonocara saulosi and Aulonocara steveni — and overhauled the boundary between Aulonocara and Trematocranus, transferring several Trematocranus species into Aulonocara after showing that the old diagnostic characters (the degree of swelling of the infraorbital sensory cavities, the number of cheek scale rows, the presence or absence of flank spot-series) occurred in too many variable combinations to define the genera. The type locality is the east coast of Chizumulu Island, Lake Malawi. The species has remained in its original combination, Aulonocara korneliae, with no junior synonyms, and the Cichlid Room Companion places it in the genus's "stuartgranti" group under the curatorship of Ad Konings. Original material was figured and the name registered in ZooBank; the original description gives the type series and meristics, though the holotype's museum register is not reproduced on the public secondary sources consulted here.
Morphology
This is a modestly sized peacock. FishBase records a maximum of 3 in standard length, while Konings's field-guide accounts on malawi.si give larger total-length figures of up to about 4.5 in for males and 4 in for females — the gap is mostly the difference between standard and total length plus well-fed aquarium fish, and both descriptions agree this is a small-to-medium Aulonocara. The body is the typical peacock shape: moderately deep, laterally compressed, with the steep forehead and the large, downward-angled mouth lined with the expanded cephalic lateral-line pores that the sand-foraging Aulonocara use to detect prey. Sexual dimorphism is pronounced. Territorial males turn metallic blue over the head and flanks and, distinctively, develop a clear orange to orange-gold flush on the shoulder when in full breeding colour, with egg-spots (ocelli) in the anal fin; females and non-breeding fish stay small, drab and cryptically barred in browns and greys, as is the rule across the genus. The orange shoulder and the distinct anal-fin egg-spots are the practical features that separate Aulonocara korneliae from its close relative Aulonocara hueseri of Likoma Island, which is smaller, slightly shallower-bodied and lacks the orange shoulder. Konings notes that captive fish are prone to laying down excess fat, showing as rounded contours and bulges behind the head if overfed.
Habitat
Aulonocara korneliae is endemic to Lake Malawi and, within it, restricted to Chizumulu Island — a small island near Likoma in the lake's northern half, lying close to the Mozambican shore but politically part of Malawi. The IUCN assessment, authored by Konings, treats it as known from a single location with an estimated area of occupancy of just 17 mi², distributed all around the island including its reefs and the satellite Membe Island; malawi.si documents named local populations at Same Bay, Chilongo Bay and around the island generally. The fish occupies the "intermediate" habitat — the transition zone where rocky outcrops meet open sand — and is a shallow-water specialist. It is regularly encountered near rocks but forages over the sand, typically between about 3 and 33 ft depth; it prefers roughly 33 ft of water and appears genuinely absent from the deeper reefs, rarely occurring below about 39 ft and not recorded deeper than 66 ft. Lake Malawi's surface water is warm and hard-alkaline; FishBase lists a thermal envelope of about 73–81 °F for this species. As an island endemic confined to shallow intermediate habitat, its entire world range is extraordinarily small.
Feeding
Like the rest of the sand-dwelling Aulonocara, Aulonocara korneliae is a benthic invertivore that hunts by sensory probing rather than by sight or by sifting mouthfuls of sand. It hovers just above the bottom and detects the movements of small invertebrates and crustaceans buried in the substrate using its enlarged, fluid-filled cephalic lateral-line canals and pores, then darts down to snap up the prey it has localized. FishBase summarises its biology as 'regularly found over pure rocky habitats, but forages over sand,' feeding on sand-dwelling invertebrates, and estimates a trophic level near 3.5. In the Chizumulu community it fills the same role its many congeners fill elsewhere in the lake — a specialised micro-predator of the sand–rock interface — which is one reason the peacocks have radiated into so many narrowly localised forms around the lake's reefs and islands without directly competing.
Mating
The species follows the lek-like social system characteristic of the sand-dwelling peacocks. Outside breeding it is a placid, low-aggression fish; females and immature males gather in foraging schools that commonly number more than twenty individuals, ranging over the sand together. When ready to breed, males leave the school and establish territories along the boundary where sand meets rock, each territory centred on a cave among the rocks or on the sheltered horizontal space beneath a suspended rock or overhang. There the male displays his blue-and-orange breeding colours to passing females and defends his patch against rival males; aggression is otherwise low and is essentially confined to these breeding males. This is the pre-spawning structure — receptive females visit the displaying males at their territories, and pairing is transient rather than a lasting bond.
Breeding
Aulonocara korneliae is a maternal (ovophilic) mouthbrooder, as are all Aulonocara. Spawning takes place in or beside the male's territory at the sand–rock edge: the female lays a small clutch, takes the eggs into her mouth, and the male fertilises them in the open-mouth fashion typical of Malawi haplochromines, often aided by the egg-spots on his anal fin. The female then carries and broods the developing eggs and larvae in her buccal cavity for the usual several weeks, releasing free-swimming fry once they are developed, after which there is no further biparental care — the male contributes only territory and gametes. Specific wild clutch counts and brooding durations for this species are not documented in the public literature consulted; the figures that exist are the general Aulonocara pattern (small clutches of a few dozen eggs, brooding on the order of three weeks). In aquaria it breeds readily for a peacock given sand, rockwork forming caves, and a harem of one male to two or more females.
In the aquarium
Aulonocara korneliae is a seldom-exported peacock — it surfaces in specialist shops and among hobbyists who seek out rarer Malawi cichlids, but it has never been a mainstream item, and obtaining it typically requires a dedicated importer or a breeder who works specifically with Chizumulu Island fish. Difficulty in the aquarium is low to moderate, about standard for the sand-foraging Aulonocara: it is not fragile, but it does demand the hard, alkaline water chemistry of Lake Malawi and will decline slowly in soft or acidic conditions. Target pH 7.8–8.6 and a temperature of 73–81 °F; the upper end of that range (77–81 °F) suits breeding best. Aim for a total hardness of at least 10–15 °dH and carbonate hardness in a similar range to buffer the pH. Regular partial water changes — 20–25 % weekly — matter more than the exact target numbers, because accumulating nitrates and loss of buffering capacity are the most common routes to unexplained health decline in Malawi cichlids.
For a species whose males reach roughly 4.5 in total length (females somewhat smaller), a tank of at least 59 in / 5 ft in length and 65 US gal is a reasonable minimum, and a 71–78.5 in tank comfortably supports a harem colony. The floor plan matters: Aulonocara korneliae, like its congeners, needs open sandy areas in which to forage. A substrate of fine, pale aragonite or pool-filter sand — 2 in deep at minimum — should cover the majority of the bottom, with rockwork (slate, limestone, river cobbles) arranged along the sides and back to create caves and overhangs. This mimics the sand–rock interface the fish occupies at Chizumulu Island and gives both the territory-holding male and brooding females shelter without sacrificing the open foraging floor. Avoid planting: Lake Malawi is not a planted-tank environment, and most aquatic plants struggle at the pH the fish requires. Robust hornwort or Vallisneria tolerate the water chemistry and can be included if desired, but they are not necessary.
Keep Aulonocara korneliae in a harem of one male and at least three females — ideally more — to distribute the male's attention and reduce the harassment that a single female or pair would experience. Males in breeding colour are persistent in their courtship and will badger an unresponsive female relentlessly. Additional females, or a larger tank with broken sightlines in the rockwork, reduces this considerably. As a non-mbuna peacock, Aulonocara korneliae is broadly compatible with other non-aggressive Malawi cichlids of similar or larger size: other Aulonocara species (with the caveat below), non-aggressive Copadichromis, Nyassachromis, and the more placid utaka haplochromines, as well as Synodontis catfish from East Africa. Avoid mbuna, which are far too aggressive and territorial for this fish, and avoid any fish that requires soft or acidic water.
The hybridisation risk is the most important keeper responsibility. Aulonocara species — and this is a well-documented problem in the genus — will interbreed readily in captivity, producing fertile hybrids that are difficult or impossible to distinguish by eye from wild-type fish. Aulonocara korneliae can cross with any other Aulonocara kept in the same tank. The only reliable safeguard is species-only Aulonocara keeping: run one Aulonocara species per aquarium, or choose tankmates entirely outside the genus. Hybrid peacocks are common in the trade, and one of the reasons Aulonocara korneliae lacks a stable market presence is that the "Blue Gold" label has been applied to various hybrids over the years. Serious keepers source wild-caught or F1 breeder stock from verified lines.
Breeding is straightforward once the tank is correctly set up. A territory-holding male will display before the females and spawn with a receptive one at the sand–rock edge, typically near a cave. The female broods the eggs and fry alone for roughly three weeks; the male plays no role once fertilisation is complete. To raise a brood, remove the brooding female to a separate tank before she releases fry, or provide dense rockwork in which fry can hide. First foods for free-swimming fry are newly hatched brine shrimp and fine-ground flake or cichlid micro-pellet. The single most common keeper mistake with this and similar species is overfeeding: the rounded, fat-padded look that Konings specifically flags in Aulonocara is almost entirely a product of too much food or food that is too protein-dense. Feed sparingly — once a day, or twice in small amounts — and vary the diet between good-quality sinking cichlid pellets, frozen Mysis or brine shrimp, and the occasional Daphnia or mosquito larvae.
Conservation
The IUCN Red List assesses Aulonocara korneliae as Least Concern (assessed 22 June 2018 by Ad Konings, reviewed by Jos Snoeks; published 2018), an upgrade from its previous listing of Vulnerable in 2006. The rationale is nuanced: the species is genuinely a single-location, narrow-range endemic — area of occupancy and extent of occurrence are both put at only 17 mi², which on range alone would meet the area thresholds for a threatened category — but it is common all around Chizumulu Island, its population trend shows no detected decline, and the only identified pressure, collection for the ornamental aquarium trade, has had no apparent impact on the population over roughly four decades. Konings notes in the Cichlid Room Companion that the rocky terrain around Chizumulu prevents the use of large beach seines, which further limits harvesting pressure. It carries no CITES listing. The longer-term caveat is the one that applies to every Lake Malawi endemic: a tiny island range leaves no geographic buffer, so any future change — intensified or less selective collecting, pollution, sedimentation, or the lake-wide stresses of overfishing and a warming, more stratified lake — would fall on the species' entire world population at once. Monitoring of the population trend is the recommended conservation action.