Taxonomy & naming
The species was described in 1984 by Manfred K. Meyer and Manfred Schartl as Pseudotropheus (Maylandia) hajomaylandi, in the Revue Française d'Aquariologie et de Herpétologie (volume 11, pages 51-55), from material collected at the Isle of Chisumulu (Chizumulu Island) in Lake Malawi. In their account the authors compared it with the other zebra-like Pseudotropheus of the lake — aurora, greshakei, livingstonii, lombardoi and zebra — and placed all of them, hajomaylandi included, in the subgenus Maylandia, a name they coined in the same work for the brassy 'zebra' group. That subgenus has since had a turbulent history. Maylandia was treated as a full genus by some workers but was ruled a nomen nudum at its 1984 introduction; in 1997 Stauffer, Bowers, Kellogg and McKaye erected the genus Metriaclima for the blue-black zebra complex, and Konings (2016) and Stauffer's group continue to use Metriaclima. The result is a long-running, still-unsettled nomenclatural split: FishBase and many hobbyists carry the fish as Maylandia hajomaylandi, while the IUCN and the Stauffer/Konings literature list it as Metriaclima hajomaylandi. Both refer to the same fish, and the original combination Pseudotropheus hajomaylandi remains its senior synonym. In the trade the species is most often sold simply by its scientific name, or under the older label 'Pseudotropheus Greberi'. No museum register number is repeated here because it was not confirmed in a source consulted; the type locality at Chizumulu Island anchors the name.
Morphology
This is a modestly sized mbuna with the elongate, streamlined body typical of fish that thread between boulders. Reported maximum size is about 4.5 in total length (FishBase, and the IUCN assessment), with field workers noting smaller wild figures — roughly 4 in for males and 3.5 in for females — while well-fed aquarium males commonly overshoot the wild ceiling and reach 6.5 in or more, a difference usually attributed to rich captive feeding rather than any change in the fish. Coloration is strongly sex- and mood-dependent. Dominant males take on a steel-blue to greyish-blue ground crossed by roughly seven to ten dark vertical bars, with a yellow-to-orange flush over the head that can spread onto the belly, pelvic fins and tail. Females and subadults are far plainer: a yellowish to beige-brown base with the barring only faintly expressed, so a foraging group of females reads as drab against the rocks. Juveniles resemble females. The barred blue-and-orange male is the species' diagnostic look within the Chizumulu mbuna community, where it shares the rocks with congeners such as Maylandia aurora; the two were historically confused, and the species circulated in the 1990s under the 'aurora' label.
Habitat
Maylandia hajomaylandi is a Lake Malawi endemic with one of the most restricted ranges of any mbuna: it is known only from Chizumulu Island and its immediately associated reefs and islets in the northeastern part of the lake, including features such as Chiwi Rocks and Linganjala Reef. The IUCN puts the combined length of suitable shoreline and reef habitat at about 12 mi and the area of occupancy at roughly 17 mi squared. Within that small world it is a fish of the intermediate habitat — the transition zone where scattered rocks sit on or give way to a sandy floor — and is especially associated with sediment-rich rocky bottoms, recorded mainly at depths of about 33–98 ft. It forages close to the rocks rather than ranging into open water, retreating to cover at any disturbance. Lake Malawi is hard, alkaline and thermally stable: in-situ and reference figures give a pH in the high-7s to mid-8s, a temperature of roughly 24-28 C in the upper water column, and a moderate-to-high carbonate hardness (FishBase cites pH 7.5-8.3 and 10-20 dH). These are the conditions any captive population must mimic.
Feeding
Like most mbuna, hajomaylandi makes its living off the aufwuchs — the dense felt of algae, diatoms and the tiny invertebrates living within it that coats every sunlit rock in the lake. It scrapes and combs loose strands and diatoms from the rock surface, and territorial males in particular feed from this rock biocover within their patch. But it is not a strict rock-grazer: both Konings' field observations and FishBase note that it also takes plankton from the open water just above the substrate, making it a flexible algae-and-plankton feeder rather than a narrow trophic specialist. FishBase places it at a trophic level near 3.4. That dual strategy — graze the biocover, then pick plankton when it drifts past — suits the patchy intermediate zone it occupies, where neither thick algal turf nor open-water swarms are guaranteed. In the wider Chizumulu community it is one of many mbuna partitioning the same rocky resource, its restriction to the sediment-rich intermediate zone being part of how it avoids head-to-head competition with the lake's more specialized scrapers.
Mating
Reproduction is organized around male-held rock territories, as in the mbuna generally. A breeding male defends a small cave or crevice among the rocks close to the sand floor, advertising it with his brightest steel-blue-and-orange coloration and driving off rival males; females, by contrast, occur singly or in small loose foraging groups and move through the males' territories. When a male detects a ripe female he intensifies his display — fins spread wide, body quivering — and leads her toward a spawning spot on the sand or within his cave. The species is decidedly aggressive intraspecifically, males especially so, and that pugnacity is the central fact of keeping it: in confinement a male will harass females and fight other males relentlessly. It is, however, generally no more hostile to other mbuna species than is normal for the group. The mating system is polygynous — a single male will spawn with several females in succession — which is why keepers run it as a harem.
Breeding
Maylandia hajomaylandi is a maternal mouthbrooder, the reproductive mode shared by essentially all Malawi mbuna. Spawning follows the classic 'T-position' circling: the female lays a small batch of eggs on the substrate, takes them up into her mouth, and — cued by the egg-spots on the male's anal fin — collects his milt to fertilize the clutch she already holds. Clutches are small, typically on the order of 15 to 30 eggs, consistent with the modest body size. The male's role ends at fertilization; the female alone broods, sheltering among the rocks and eating little or nothing while the eggs develop and hatch inside her mouth. Free-swimming fry are released after roughly 18 to 21 days, by which point they can graze fine algae and take crushed foods. There is no biparental care and no fixed nest beyond the spawning site; the brooding female is the entire parental investment. In the wild this mouthbrooding strategy, combined with the species' tie to a single island, keeps recruitment local — one reason the population has stayed stable but geographically pinned.
In the aquarium
Maylandia hajomaylandi is an infrequently seen fish in the hobby — it surfaces periodically from specialist breeders and cichlid-focused shops, but does not enjoy the steady availability of workhorses like Maylandia zebra or Metriaclima estherae. Keepers willing to track it down will find a moderately challenging mbuna: not a fish for a beginner's community tank, but manageable for anyone experienced with the Lake Malawi rock community. A 1.2-metre (four-foot) tank is a workable minimum for a single male with two or three females; 5 ft (five feet) and up is strongly preferred, and necessary for mixed-species displays. The filtration must be robust — mbuna are messy, active foragers — and regular water changes of 20–25 % weekly keep nitrate and dissolved organics in check.
Water chemistry must mirror Lake Malawi: a pH of 7.7–8.6, temperature between 24 and 82 °F, and moderate to high carbonate hardness (roughly 10–20 dH). In most tap-water areas some degree of buffering is needed, either with commercial Malawi salts, a limestone aggregate in the filter, or crushed coral/aragonite substrate — any of which stabilises the pH in the upper 7s to low 8s that this fish requires. The substrate proper should be fine sand or small gravel, reflecting the intermediate sandy-rocky zone it inhabits in the wild. Rockwork is essential: the tank should offer a substantial pile of boulders with multiple caves, overhangs and crevices, both to break sightlines and to let females escape a persistent male. Dense planting is counterproductive and unnecessary; African cichlid enthusiasts typically leave large open sandy areas between the rock structures.
The species is territorial and aggressive in the manner typical of the zebra complex. A single male will claim and defend the best cave site and will harass females incessantly unless given enough space and retreats. Keeping more than one male in a tank below 6 ft almost always ends in one being killed or chronically stressed, so the standard recommendation is one male to two or three females. Mixed-species mbuna communities are possible but require careful selection: tankmates should be of broadly similar size, from different genera if possible (to reduce the visual stimulus of closely matching colour patterns), and the total stocking density should be high enough to spread aggression without overloading the filtration. Species with very similar blue-barred male coloration — including other Metriaclima/Maylandia variants — are best avoided, as males will direct intense aggression toward visually similar rivals.
Diet is a point of real importance with this species. Like all mbuna it is an aufwuchs grazer, which means the bulk of its diet should be high in vegetable matter: spirulina-based flakes or pellets, blanched spinach, nori, and similar plant-based foods should make up around 70–80 % of meals. Standard high-protein foods — beef heart, bloodworm, most krill-heavy cichlid pellets — carry well-documented risk of Malawi bloat, a rapidly progressing bacterial or immune-related gut inflammation that is among the leading causes of mbuna deaths in captivity. The mistake is common among keepers transferring habits from other cichlid groups; with mbuna it is worth resisting entirely. Feeding small amounts two or three times daily mimics the constant grazing of the wild fish better than one large daily meal.
Breeding in captivity follows naturally once a compatible group is established and water quality is stable — the species is a maternal mouthbrooder with the standard mbuna sequence of spawning, egg pickup, and a buccal brooding period of roughly 18–21 days. A brooding female will eat little and benefits from a quiet area away from the male; many keepers move her to a separate, bare-bottomed 'fry saver' tank once brooding is confirmed. Fry released after the hold are large enough to take crushed spirulina flake and newly hatched brine shrimp immediately, and grow well at normal mbuna temperatures. Given the species' limited trade availability, captive-bred stock from specialist breeders is the more reliable and conservation-appropriate source than wild-caught imports.
Conservation
The IUCN Red List assesses the species (as Metriaclima hajomaylandi) as Least Concern, last assessed on 20 June 2018 by Ad Konings and reviewed by Jos Snoeks. That is an upgrade from earlier listings of Vulnerable in 2006 and 2017: although its tiny range — endemic to Chizumulu Island, with an area of occupancy near 17 mi squared — meets the spatial thresholds that would otherwise flag it as threatened, the assessment found no detectable population decline across roughly four decades of collection for the aquarium trade, which is the only identified threat. It remains a common fish of the intermediate habitat all around the island and its reefs, and carries no CITES listing. The caution lies in how concentrated it is: a species confined to one small island's rocky margins has no refuge population to fall back on, so any localized shock — a collapse in trade controls, sedimentation from shoreline disturbance, or a sharp change in the near-shore environment — would bear on the entire global population at once. That sits within the broader strain on Lake Malawi, where catchment deforestation, sediment and nutrient loading, climate-driven warming and reduced deep mixing, and heavy fishing pressure are documented stressors on the lake's near-shore communities. None of these is recorded as a present decline for hajomaylandi, but they are the backdrop against which a single-island endemic should be read.