Taxonomy & naming
Aulonocara sp. "Blue Chilumba" is not a formally described species. It has no scientific name of its own, no describing author, no year of publication, and no entry in Eschmeyer's Catalog of Fishes, because no taxonomist has published a description establishing it. It is an informal taxon recognised in the aquarium and field literature, principally through the work of Ad Konings in his Malawi cichlid books and on the Cichlid Room Companion. The placeholder name follows the standard convention for undescribed cichlids — the genus Aulonocara, the abbreviation "sp." (species), and a descriptive name in quotation marks combining a colour and a locality: "Blue Chilumba," for the deep-blue males found at Chilumba in the northern lake. Konings places the fish firmly within Aulonocara on anatomical grounds, since it carries the genus's diagnostic enlarged cephalic sensory pores — the widened lateral-line canals of the head that define the peacocks. It belongs to the broad assemblage of blue-bodied peacocks allied to the Aulonocara stuartgranti complex, of which the northern lake holds a series of locality colour forms. Until a formal revision is published it should be regarded strictly as a Konings-recognised undescribed form, and no authority or date should be attached to it.
Morphology
This is a medium-sized peacock on the standard Aulonocara plan: a moderately deep, laterally compressed haplochromine body carrying the genus's characteristic head, in which the lateral-line canals of the face are widened into conspicuous sensory pits. Field and hobby references place mature males at roughly 4.5–5 in and females somewhat smaller, the usual peacock arrangement in which males run a little larger. Sexual dichromatism is pronounced. Dominant, sexually active males are a deep, saturated blue across the head and flanks, frequently with the darker vertical barring that runs through the blue peacocks, and they hold this nuptial dress year-round rather than only at spawning. Females and subordinate, non-territorial males are far plainer — smaller, silvery-brown and cryptically marked. Because the form is undescribed, no formally published character cleanly separates it from other blue peacocks; the working distinction rests on collection locality (Chilumba) and the particular depth and tone of the male blue.
Habitat
Aulonocara sp. "Blue Chilumba" occurs in the northern part of Lake Malawi, documented from the rocky coast around Chilumba. Its biotope is the classic Aulonocara intermediate habitat — scattered rocks standing on an open sandy floor, the transitional zone the peacocks favour, rather than continuous rock or pure sand. The water is the warm, hard, strongly alkaline medium typical of Lake Malawi's upper and middle water column: temperatures broadly in the mid-20s Celsius, pH on the alkaline side of neutral, and moderately hard to hard general hardness. Like most sand-associated peacocks it forages over the open sand between and around the scattered rocks, in the moderate depths characteristic of the stuartgranti-group locality forms. As an undescribed, locality-based form its full distribution beyond the Chilumba area is uncertain.
Feeding
Aulonocara sp. "Blue Chilumba" is a sand-sifting micro-invertivore, feeding in the manner that defines the peacock radiation. It hovers just above the open sand and holds still, the enlarged sensory pores on its head — part of the ampullary lateral-line system — registering the faint vibrations of small invertebrates moving within the substrate. When prey is detected the fish darts down, takes a mouthful of sand, sifts out the edible items, and expels the spent grains through the gills and mouth. The diet is the genus-typical menu of small benthic invertebrates: insect larvae, micro-crustaceans, and other soft-bodied animals living in the sediment. This sensory, bottom-oriented hunting mode ties the fish to clean, invertebrate-rich sand and is shared across the blue peacocks of the northern lake to which the form belongs.
Mating
Like all Lake Malawi peacocks, Aulonocara sp. "Blue Chilumba" is understood to be polygynous and lek-like in its social organisation, with no pair bond. Males in nuptial colour establish and defend small territories on or near the sandy floor, each centred on an excavated pit or a sheltered spot among scattered rocks, and display from these sites to passing females. Females are not territorial; they move across the substrate singly or in loose groups and visit the displaying males. A ripe female approaches a colour-holding male at his site, and courtship follows the conventional haplochromine pattern of lateral display and quivering that leads the female to spawn. Because males hold their bright blue colour year-round, the lek is effectively always active. The specific details of this form's wild reproduction have not been separately documented, since it is an undescribed population understood chiefly by analogy with its better-known relatives in the stuartgranti complex.
Breeding
Aulonocara sp. "Blue Chilumba" is a maternal mouthbrooder, as are all Lake Malawi peacocks. After a male's courtship draws a willing female to his spawning site, she deposits a small batch of eggs and immediately takes them into her mouth; she is then drawn to the egg-spot markings on the male's anal fin and, in attempting to gather these false "eggs," takes in milt that fertilises the clutch already held in her buccal cavity. The female broods the eggs and larvae in her mouth for roughly three to four weeks, ceasing to feed for most of that period, before releasing free-swimming fry; there is no biparental care and no further parental investment once the young are released. Clutch size has not been documented specifically for this form, but by analogy with similarly sized peacocks it is expected to be modest, on the order of a few dozen eggs. Blue peacocks of this group breed readily in captivity.
In the aquarium
Aulonocara sp. "Blue Chilumba" is a northern-lake blue peacock that appears in the trade as a locality colour form, prized for the depth of its male blue. When it is kept, its requirements follow the general template for an open-sand Lake Malawi peacock.
The tank should provide a fine sand substrate — at least 2 in deep — over a generous open footprint, since this is a sand-sifting fish that needs room to hover and forage; coarse gravel inhibits the sifting behaviour and can damage the gills. A footprint of at least 47 in is a sensible minimum, with a background of stacked rock providing broken sightlines and a few bolt-holes while leaving most of the floor open. Water chemistry should mirror Lake Malawi's water column: 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. Prolonged exposure to soft or acidic water causes chronic problems in Malawi cichlids and should be avoided.
Because males are permanently in nuptial colour and perpetually willing to spawn, a single male with several females is the standard, lowest-stress arrangement; a lone male in a bare tank will harass unreceptive females relentlessly, so generous space and broken sightlines matter. Diet should be the usual varied peacock menu — a quality cichlid pellet or flake as a staple, supplemented with small frozen or live invertebrates such as chironomid larvae, brine shrimp, and daphnia. Fatty foods should be avoided, as they predispose Malawi cichlids to bloat, and regular partial water changes keep nitrate low. Because blue peacocks of different localities are visually similar, keepers who intend to breed the Chilumba form should keep it apart from look-alikes to preserve the locality line.
Conservation
Aulonocara sp. "Blue Chilumba" has not been evaluated by the IUCN, and because it is an undescribed form without a formal scientific name it has no Red List assessment of any kind — no status, no category, no published criteria. That absence is a statement about taxonomy, not about safety. As a locality-based northern-lake form it is exposed to the same general pressures as other Lake Malawi cichlids: ornamental collection, inshore habitat disturbance, and the broader stresses of sedimentation and fishing across the basin. No fabricated conservation status should ever be attached to it. The honest statement is simply that it is unassessed and that its true range and status remain to be established by formal study.