Taxonomy & naming
Chindongo sp. "Elongatus Nkhata Blue" 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. It belongs to the elongatus complex - a group of small, rock-dwelling mbuna anchored by Chindongo elongatus (Fryer, 1956), the type species of the group as defined by Ribbink and colleagues in 1983, and now placed in the genus Chindongo, which Shan Li, Ad Konings and Jay Stauffer erected in a 2016 Zootaxa revision by splitting a cluster of species out of Pseudotropheus. The confirmed range of the true, described Chindongo elongatus is restricted to the north-eastern Tanzanian shore around Mbamba Bay; the elongatus complex as a whole, by contrast, spans more than thirty named and undescribed forms scattered across Malawian, Mozambican and Tanzanian shores, most distinguished from one another chiefly by colour and locality rather than by any formally published anatomical character. Chindongo sp. "Elongatus Nkhata Blue" is one of these undescribed locality forms, recorded from the Nkhata Bay area of the north-western Malawian shore as a blue-dominant male colour variant, distinguished in field references from the brown-toned population recorded at the same general locality (Chindongo sp. "Elongatus Nkhata Brown"). Field workers and hobbyists recognise it through malawi.si and Ad Konings's survey work rather than a taxonomic publication, and until the complex receives a fuller revision, no authority or date should be attached to it.
Morphology
This form follows the standard elongatus-complex build: a proportionally slender, laterally compressed body, elongated relative to the deeper-bodied mbuna typical of the rest of the genus. Genus/complex-typical size runs to roughly 3.5 in standard length in the wild (up to about 5.5 in total length reported for aquarium-grown fish of the complex), males usually somewhat larger than females. Field references and the trade name mark this population's dominant males as blue-toned, consistent with the elongatus complex's well-documented pattern of extreme colour divergence among populations that are otherwise very similar in body shape - colour, in this group, functions as the identity that separates one locality form from the next. Females and subordinate males are expected to be considerably plainer, as in Chindongo elongatus generally. Because the form is undescribed, no formally published character beyond collection locality and this reported male colour separates it from other members of the complex.
Habitat
This form is recorded from the Nkhata Bay area, on the north-western shore of Lake Malawi. Like other members of the elongatus complex it is expected to occupy shallow, sediment-free rocky habitat - crevices and small caves among boulders and coarse rubble, with little or no silt, since the algal biofilm coating these surfaces is the food supply and sedimentation that smothers the rock directly degrades it. No depth range specific to this population has been published; genus/complex-typical elongatus habitat runs from roughly 2–49 ft. The overlying water is the warm, hard, strongly alkaline chemistry universal to Lake Malawi's surface layer: broadly 24-28 degC and pH 7.7-8.6. No water measurements specific to this population have been published; habitat-typical values are used here and flagged as such.
Feeding
Chindongo sp. "Elongatus Nkhata Blue" is presumed to be an aufwuchs grazer, as is Chindongo elongatus and the wider complex: combing loose algae and diatoms from the biofilm that coats sunlit rock surfaces, using comb-like teeth adapted for rasping rather than crushing. FishBase places the nominal species at a trophic level around 2.5, consistent with a near-herbivorous diet dominated by plant material and microorganisms scraped directly from rock. As with virtually all aufwuchs-grazing mbuna, a predominantly vegetable diet is expected to matter for this form's long-term health, since a protein-heavy diet is a recognised cause of Malawi bloat in captive mbuna. No feeding study specific to this population has been published; this account follows the well-documented elongatus-complex pattern.
Mating
Chindongo sp. "Elongatus Nkhata Blue" is presumed to follow the polygynous, lek-like mating system typical of Chindongo elongatus and the wider mbuna assemblage, with no lasting pair bond. In the nominal species, an unusually structured arrangement has been documented in which females hold the primary algae-grazing territories and males position themselves within or adjacent to those territories to court, rather than the simpler male-dominant system typical of many other mbuna genera; whether this population follows the same pattern has not been separately confirmed. Courtship in the complex generally follows the standard haplochromine template: a displaying male leads a ripe female to a spawning site, she deposits eggs and gathers them into her mouth, then is drawn to the male's anal-fin egg-spot ocelli and picks up milt that fertilises the clutch she is already carrying.
Breeding
Chindongo sp. "Elongatus Nkhata Blue" is presumed to be a maternal mouthbrooder, as are all Chindongo. Following the genus pattern, the female alone broods the clutch after fertilisation, taking little or no food during the brood period and holding the developing eggs and larvae for roughly three to four weeks before releasing free-swimming fry able to fend for themselves; there is no male or biparental care beyond fertilisation. FishBase records fecundity of up to about 37 eggs per spawn for the nominal species, consistent with the small clutch sizes typical of Chindongo generally. No clutch data specific to this population have been published.
In the aquarium
Chindongo sp. "Elongatus Nkhata Blue" is kept, where it appears in the trade, following the general Chindongo elongatus-complex template: a rockwork-dominated aquarium with a continuous chain of caves, crevices and overhangs, a footprint of at least 47 in for a single male with a harem of females, and water matched to the Lake Malawi standard - pH 7.8-8.6, temperature 24-28 degC, and reasonable hardness to buffer the pH. Stability matters more than precision; large swings in pH or temperature stress mbuna and invite disease, and weekly partial water changes of around 25-30% are standard practice.
Diet should lean strongly vegetable - spirulina flake, nori, blanched greens - with animal protein kept to an occasional treat, since a protein-heavy diet is a well-documented cause of Malawi bloat in this group. Males of the elongatus complex are among the more aggressive mbuna, so a harem of at least four to six females per male, generous rockwork, and broken sightlines all help manage within-species aggression; slower or more retiring tankmates are poor companions. Because the elongatus complex interbreeds freely across its many locality forms, Chindongo sp. "Elongatus Nkhata Blue" should not be mixed with other elongatus-complex fish - keep the collection point on record and keep forms separate rather than representing a location variant as the nominal species.
Conservation
Chindongo sp. "Elongatus Nkhata Blue" has not been evaluated by the IUCN. As an undescribed form it has no Red List category, status, or assessment of any kind - a statement about taxonomy, not about safety in the wild. The nominal species, Chindongo elongatus, is assessed Near Threatened on the strength of a very restricted confirmed range around Mbamba Bay and Hongi Island in Tanzania, with sedimentation from agricultural run-off identified as the specific threat to the algal biofilm the fish depends on; that assessment applies to the described species alone and cannot be extended to this separately recorded population. As a rocky-shore mbuna, this form is exposed to the general pressures on Lake Malawi's littoral cichlid fauna - shoreline sedimentation, ornamental collection, and the broader basin-wide strain documented across the lake. No conservation status beyond "not assessed" should be attached to it.