Taxonomy & naming
Maylandia sp. "Aggressive Greyhead" has no describing author and no entry in Eschmeyer's Catalog of Fishes; it is a hobby and locality-database trade name, not a validated scientific one. Maylandia is the genus into which most of the Lake Malawi "zebra-complex" mbuna were moved, honouring the German aquarist and author Hans J. Mayland; several of its species were long carried under Pseudotropheus before the split. The genus is large, colour-polymorphic across localities, and includes numerous undescribed local forms distinguished by subtle differences in head and body colour rather than by measurable characters. The "aggressive" qualifier in this trade name follows a documented convention among Malawi cichlid collectors and researchers, who have used behavioural labels to distinguish superficially similar mbuna forms occurring at the same locality when colour alone does not reliably separate them; it implies this form was noted as more territorial or combative than a co-occurring look-alike at Nakantenga Island, though the specific comparison has not been documented in the sources consulted here.
Morphology
"Aggressive Greyhead" is expected to share the standard Maylandia build: a moderately deep, laterally compressed body with a blunt head and a mouth positioned for scraping algae from rock surfaces, the typical mbuna body plan. As the name implies, the head is reported to carry grey colouring, likely contrasting with a different body tone, but the full pattern has not been formally described. Genus-typical size for Maylandia mbuna runs to roughly 3.5–4.5 in total length; no validated maximum has been published for this form specifically. Breeding males would be expected to show the strongest expression of the grey head colouring, with females typically duller and, in many Maylandia species, carrying a different base colour altogether.
Habitat
Nakantenga Island is a small, rocky island locality on Lake Malawi's central-west shore in the general vicinity of Senga Bay, offering the steep rock faces and boulder fields typical of mbuna habitat. "Aggressive Greyhead" was recorded there; specific depth data are not available, but genus-typical Maylandia occupy the rocky shallows from roughly 7–49 ft, sheltering in crevices and holding territory over favoured feeding rocks. Mbuna in general show strong site fidelity, rarely moving more than a few dozen metres from a home rock pile over a lifetime — a pattern of limited dispersal identified by early Lake Malawi researchers such as Ribbink and colleagues as a key driver of the group's extraordinary local diversification, since populations on separated rock outcrops become genetically isolated from one another even at short distances.
Feeding
As in other Maylandia, this form is presumed to be an aufwuchs grazer, scraping the algal film and associated diatoms and small invertebrates from rock surfaces with specialised, closely packed teeth. No feeding study specific to this form has been published, but there is no reason from genus placement to expect a different diet. Mbuna dentition is adapted for this grazing lifestyle: numerous small, closely packed teeth arranged in rows are shed and replaced continuously through life, and different mbuna genera and species partition the same rock surface by targeting algae at different depths within the aufwuchs mat, a trophic specialisation documented across the group since Fryer and Iles' influential 1972 ecomorphological study.
Mating
Maylandia breeding follows the standard mbuna pattern: males hold and defend a cave or rock crevice territory against rivals, displaying to females that enter to inspect the site before spawning. The "aggressive" element of this form's trade name suggests unusually vigorous territorial defence, consistent with general mbuna courtship and territorial behaviour, though no direct observation of this specific form's mating behaviour has been published. As in essentially all Malawi mbuna, courting males are expected to display the egg-spot markings on the anal fin that mimic eggs, prompting the female to mouth at them during spawning and draw in sperm to fertilise the clutch she is already collecting.
Breeding
Reproduction is maternal mouthbrooding, as in all Maylandia: spawning takes place at the male's territory, after which the female collects the fertilised eggs into her mouth and carries the developing brood alone for roughly three weeks before releasing free-swimming fry. Clutch size has not been documented for this form; genus-typical broods run to roughly 12–40 eggs depending on female size. Incubation at typical Lake Malawi temperatures runs close to three weeks, during which the brooding female feeds little if at all and often withdraws to a sheltered rock crevice; fry are released well developed and immediately able to shelter among the rocks.
In the aquarium
This is a scarce, locality-specific form reaching the hobby only through specialist Malawi cichlid importers. Standard mbuna care applies: a heavily rock-aquascaped tank with abundant line-of-sight breaks, alkaline, well-buffered water matching Lake Malawi chemistry, and a vegetable-forward diet to suit its grazing habit. Given the behavioural implication in its trade name, keepers should expect this form to run on the more territorial end of the mbuna spectrum and should stock tankmates and territory space accordingly, with a low male-to-female ratio to spread aggression. A tank of at least 47 in with dense, stable rockwork built to the substrate rather than resting on it, to prevent collapse, best replicates its natural territory structure, and a vegetable-based flake or pellet diet with limited protein helps avoid the digestive problems mbuna are prone to on richer foods.
Conservation
As an undescribed form, "Aggressive Greyhead" has not been assessed by the IUCN and carries no conservation status. Nakantenga Island and the wider Senga Bay area are established collection points for the aquarium trade, and mbuna populations at heavily fished, easily accessible rocky localities can be locally depleted by sustained over-collection, but no population data specific to this form are available. More broadly, this is a structural gap common to many Malawi mbuna: an undescribed, single-locality form cannot receive an IUCN assessment without a formal description, even though a population confined to one rock reef can be as vulnerable to local over-collection or habitat disturbance as many formally listed species.