Taxonomy & naming
Maylandia nigrodorsalis belongs to Maylandia (also known in older and hobby literature as Metriaclima), the genus holding Lake Malawi's classic vertically barred 'zebra' mbuna, split away from the broader, now much-reduced Pseudotropheus. The genus honours the German aquarist and cichlid author Dieter Mayland. The species epithet nigrodorsalis combines the Latin niger (black) with dorsalis (of the back, dorsal), naming a black or dark dorsal fin as the species' diagnostic field character — a straightforward, descriptive naming choice common across Maylandia, where many species are distinguished from close relatives by exactly this kind of specific fin or body-region marking. The precise describing authority and date of publication are not confidently available here; readers should consult Eschmeyer's Catalog of Fishes for the definitive citation.
Morphology
Maylandia nigrodorsalis follows the compact, moderately deep-bodied zebra-mbuna plan typical of its genus, with the dense, comb-like bicuspid dentition used for scraping algae from rock. Species in this genus typically reach 3.5–5 in total length at maturity, with males usually the larger sex; a species-specific figure for M. nigrodorsalis is not confirmed here. As its name indicates, the dorsal fin is dark or black, a feature that most plausibly appears prominently in breeding males and serves as the primary field mark separating this species from similarly barred Maylandia at nearby reefs. Sexual dichromatism is expected to be pronounced, as it is throughout the genus, with females likely plainer or showing the orange-blotch (OB) polymorphism common across Maylandia.
Habitat
This species is documented from a cluster of reefs on Lake Malawi's eastern shore near the Mozambique border, including Chiloelo, Meponda, Nkhungu Point, Nkolongwe and Thundu. Like other Maylandia, it is expected to be a strict rocky-shore specialist, confined to rock and rock-sand transition habitat, with no open-water or riverine life stage. The water across this range is Lake Malawi's characteristic hard, alkaline medium, warm and well-buffered.
Feeding
Maylandia nigrodorsalis is expected to feed as an aufwuchs grazer, in keeping with the genus generally, scraping the algae-and-diatom film off sunlit rock surfaces using the dense bicuspid tooth rows characteristic of Maylandia, and supplementing this vegetable-leaning diet opportunistically with small invertebrates picked from the rock. Territorial males, restricted to the vicinity of the cave they defend, depend on the aufwuchs growing within reach of that patch of reef.
Mating
As in other Maylandia, males of this species are expected to establish and defend small cave territories among the rocks, displaying to females and driving off rivals in a polygynous mating system without pair bonding. A ripe female enters the male's territory, and courtship follows the standard haplochromine sequence of lateral display and quivering that leads to spawning near the cave. No species-specific courtship behaviour has been separately documented for M. nigrodorsalis.
Breeding
Maylandia nigrodorsalis is a maternal mouthbrooder, the reproductive mode shared by all mbuna. Following spawning, the female takes the fertilised eggs into her mouth, prompted by the egg-spot markings on the male's anal fin, and broods them alone for roughly three to four weeks before releasing free-swimming fry near cover. There is no male or post-release parental care. Clutch size has not been documented specifically for this species but is expected, by comparison with similarly sized Maylandia, to run to a few dozen eggs.
In the aquarium
Maylandia nigrodorsalis is not established in the aquarium trade under this name, and specific captive husbandry information is not available. Were it kept, care would follow the standard Maylandia template: a long aquarium of at least 47 in with dense stacked rockwork providing numerous caves and broken sightlines, water chemistry matching the lake — hard and strongly alkaline, pH roughly 7.7 to 8.6, temperature in the mid-20s Celsius — and a spirulina-based, vegetable-leaning diet to avoid the bloat that a protein-heavy regimen can trigger in Malawi mbuna. A single male with several females is the standard low-conflict grouping, and as with all Maylandia, this species should not be mixed with similar barred or OB-patterned mbuna to avoid hybridisation, particularly since its main distinguishing feature — a dark dorsal fin — can be subtle enough to overlook without careful comparison.
Conservation
Maylandia nigrodorsalis has not been assessed by the IUCN Red List, so no formal conservation status can be reported here. As a rocky-shore endemic confined to a limited stretch of Lake Malawi's eastern, Mozambican-border coastline, it is exposed to the pressures typical of narrow-range mbuna: localised ornamental collection, shoreline disturbance and sedimentation from catchment land-use change. Lake Malawi as a whole faces mounting pressure from fishing, nutrient loading and a warming climate affecting its stratification, and reef-restricted species like this one share in that basin-wide risk even without species-specific data to quantify it.