Taxonomy & naming
Nyassachromis sp. "Argyrosoma Blue" has no scientific description, no describing author or year, and does not appear in Eschmeyer's Catalog of Fishes or FishBase. Its trade name pairs a resemblance to Nyassachromis argyrosoma with a colour qualifier describing this form's breeding-male dress. Nyassachromis argyrosoma was originally described by Charles Tate Regan in 1922 as Haplochromis argyrosoma and later transferred to the genus Nyassachromis, erected by George Turner in 1994 in the broader revision of Lake Malawi's haplochromine genera that also produced Mylochromis, Stigmatochromis, and several others; argyrosoma is the type species of Nyassachromis, meaning the genus itself was built around this fish's morphology. This form at Maleri Island is presented as resembling the type species closely enough to carry its name informally, without having been confirmed as conspecific by direct comparison. No authority or publication date should be attached to it.
Morphology
As a form allied to Nyassachromis argyrosoma, this fish is expected to share the genus's slender, laterally compressed body built for open-water schooling rather than rock-holding. The genus name itself, from the Greek argyros for silver and soma for body, describes the plain silvery flank colouration typical of non-breeding fish and females — the base condition this form's "Blue" qualifier is set against. A mid-sized figure of roughly 4–4.5 in TL is consistent with other described Nyassachromis species and is a reasonable estimate here rather than a measurement taken from Maleri Island fish. Breeding males are expected, per the trade name, to develop blue body coloration, the typical nuptial dress across several Nyassachromis species, intensified with black markings during display; females and non-breeding fish remain the plain silvery colouration the genus name describes.
Habitat
The recorded locality for this form is Maleri Island, in the central-western part of Lake Malawi. Nyassachromis species are broadly open-water and sand-associated fish rather than rock specialists, forming large foraging schools above sandy and open-water habitat, often near but not confined to rocky islands like Maleri. Water in this part of the lake follows the typical warm, alkaline, well-buffered Malawi profile, with schooling activity concentrated in the upper tens of metres of the water column.
Feeding
Nyassachromis species are zooplanktivores, feeding in large mid-water schools on copepods and other zooplankton, the same general niche occupied by the lake's well-known "utaka" haps in the genus Copadichromis. This form is presumed to feed the same way, foraging in schools over open water and sand rather than picking invertebrates from the substrate, though no dedicated dietary study exists for the Maleri Island population specifically.
Mating
Several Nyassachromis species are documented for a distinctive lek-spawning behaviour in which males build conspicuous sand-castle or sand-cone structures on the lake floor and defend them in loose aggregations, a pattern noted by Ad Konings as early as the genus's first Cichlids Yearbook coverage in the early 1990s. Females remain in large foraging schools away from the spawning sites and visit only to spawn with a displaying male before returning to the school. This form is presumed to follow the same general lek pattern given its resemblance to the type species, though the specific behaviour has not been documented for the Maleri Island population.
Breeding
Nyassachromis sp. "Argyrosoma Blue" is presumed to be a maternal mouthbrooder, the universal reproductive strategy of the Lake Malawi haplochromine flock. Following the genus's documented lek-spawning pattern, a female would spawn at a male's sand structure, take the fertilised eggs into her mouth, and rejoin the foraging school to brood them through several weeks of development before releasing free-swimming fry, with no further parental care from the male. Clutch size has not been documented for this form; a modest clutch, in line with the small body size typical of the genus, roughly 20 to 40 eggs, is a reasonable estimate by analogy with congeners.
In the aquarium
This form is uncommon in the trade and has no dedicated husbandry record. A keeper who obtains it should follow genus-typical Nyassachromis practice, similar to keeping small zooplanktivorous Malawi haps: a tank of at least 47–59 in to accommodate its schooling, active nature, a sand substrate, and water matched to Lake Malawi's chemistry — roughly 75–82 °F, pH 7.7 to 8.6, well-buffered. As a schooling fish it likely does better kept in a group rather than singly, though this has not been tested for the form specifically. It should mix well with other peaceable open-water haps and peacocks.
Conservation
No IUCN Red List assessment exists for Nyassachromis sp. "Argyrosoma Blue", and none can until it is formally described. Open-water and sand-associated haplochromines in Lake Malawi generally face greater bycatch pressure from inshore seine and trawl fisheries than rock-dwelling mbuna, since their schooling, non-territorial habits make them more vulnerable to netting; whether this specific Maleri Island population is affected to any particular degree is not documented. The honest position is that it is unassessed.