Taxonomy & naming
Corematodus taeniatus is the second recognised species in the genus Corematodus, alongside the better-documented Corematodus shiranus, which George Albert Boulenger described in 1897 from the Upper Shiré River system. The genus sits within the Pseudocrenilabrinae haplochromine radiation of Lake Malawi, in the small cluster of specialised tissue-cropping genera — Corematodus and Docimodus — that twentieth-century revisions separated out from the general-purpose Haplochromis on the strength of their feeding apparatus. The species epithet taeniatus is Latin for banded or ribboned, a reference to a lateral stripe that helps distinguish this fish from C. shiranus in the field. Eschmeyer's Catalog of Fishes (California Academy of Sciences) is the standing authority for the valid name and its precise original citation; the exact describing author and year for taeniatus are not asserted here with confidence and should be checked against the Catalog before being cited.
Morphology
Corematodus taeniatus has the elongate, laterally compressed, faintly silvery body typical of the genus — a shape that, at a glance, resembles the small open-water zooplanktivores it shadows in the wild. The mouth carries fine, closely packed, often recurved teeth adapted for rasping scales rather than crushing or gripping large prey, and the head profile is comparatively unspecialised next to a heavy-jawed predator like Docimodus. The species is named for a lateral band or stripe (taeniatus, banded) that sets it apart from the plainer-flanked C. shiranus, though the exact colour and pattern differences between the two are best confirmed against current photographs rather than assumed here. As in essentially all Lake Malawi haplochromines, breeding males are expected to intensify in colour relative to females, but this species is rarely enough encountered that its dimorphism has not been well catalogued.
Habitat
Corematodus taeniatus is endemic to Lake Malawi and has been documented along the western and south-central shoreline, including the rocky habitat around Chemwezi Rocks, Mazinzi Reef and Narungu, as well as Namalenje Island, the source of the first significant aquarium-trade exports. Like other scale-eating specialists it is associated with mixed rock-and-open-water zones where its preferred prey — small shoaling cichlids it can shadow and mimic — gather in numbers, rather than with pure rock faces or pure open sand; per Konings (Enjoying Cichlids), breeding males in particular are found at small rocky outcrops that border sandy biotopes, consistent with this intermediate-zone habitat. The surrounding water is the typical alkaline, well-buffered Lake Malawi column: warm tropical temperatures through the mid-20s Celsius and a pH comfortably on the alkaline side of neutral. Beyond the documented collection points it is considered an uncommon, thinly recorded species, and its full depth range and habitat breadth are not well established in the accessible literature.
Feeding
Corematodus taeniatus is a lepidophage — a scale-eating specialist — one of only two Lake Malawi genera, alongside Docimodus, to have evolved this diet. The strategy relies on stealth rather than force: the fish's slender, silvery body and unhurried swimming style let it mingle into groups of sand-dwelling cichlids without triggering alarm, after which — usually approaching from behind, occasionally attacking from above — it delivers a sudden bite that rasps fine scales from the caudal fin and peduncle of a passing fish, rather than from the flank generally. The fin itself is rarely damaged outright, but repeated attacks leave a fish's fins visibly worn and rashy; the prey is not killed and scales regenerate, so a single population of host fish can be repeatedly cropped, a grazing-style parasitism rather than true predation. Aquarium observation backs this up directly: newly introduced, naive fish are targeted immediately and repeatedly until they learn to keep their distance — mbuna in particular learn quickly — with a stable balance typically reached only after a couple of months, by which point the scale-eater has also switched much of its feeding onto ordinary aquarium fare. This niche is thought to be a case of aggressive mimicry, in which the scale-eater's resemblance to harmless shoaling cichlids is itself the hunting adaptation.
Mating
Like the rest of the Lake Malawi haplochromine flock, Corematodus taeniatus is polygynous and non-pair-bonding, and here — unlike much of its biology — there is a direct species-specific account: per Konings (Enjoying Cichlids), breeding males are territorial and defend a spawning site on top of a rock, with most breeding males found at small rocky outcrops that border sandy biotopes, the same intermediate rock/sand zone the species favours generally. From that territory a male is expected to display to receptive females moving through in search of a spawning site, following the general courtship pattern of quivering, circling and lateral display shared across the lake's mouthbrooding cichlids, though the fine detail of that courtship display has not itself been described for this species.
Breeding
Corematodus taeniatus is presumed to be a maternal mouthbrooder, the reproductive mode used by virtually the entire Lake Malawi haplochromine radiation, including its congener and the related Docimodus. Following spawning, the female is expected to take the fertilised eggs into her mouth and brood them there through hatching and early larval development before releasing free-swimming fry, without further male involvement. Clutch size, brooding duration and fry survival have not been documented for this species specifically; given the modest size typical of the genus, a clutch on the order of a few dozen eggs would be consistent with similarly built Lake Malawi cichlids, though this is inference, not a measured value.
In the aquarium
Corematodus taeniatus has in fact reached the aquarium trade, though only irregularly and under trade names rather than its scientific one — corrected here from an earlier assumption that it was essentially unknown to hobbyists. Norman Edwards first exported the species as 'Haplochromis Jacksoni'; Stuart Grant exported it again in 1988, collected at Namalenje Island, under the name 'Haplochromis Space Mouth'. A documented keeping account (Konings, Cichlids Yearbook) describes a single freshly imported specimen, about 4.5 in long, silvery with a partially interrupted diagonal line and a notably wide, many-rowed rasping dentition, introduced into a community tank of mbuna and larger haplochromines. Within hours it began targeting the caudal fins of tankmates, mostly attacking from behind; new, naive fish introduced afterward were singled out and repeatedly attacked until they learned to keep their distance, mbuna doing so fastest, with the tank reaching a stable balance after roughly two months, by which point the scale-eater had also taken readily to standard aquarium foods.
The practical implication is that this is a fish that CAN be kept alongside other species, provided the tankmates can tolerate — and eventually learn to avoid — its scale-nipping. Konings recommends mbuna or other robust species, citing the genus Nimbochromis by name, as workable companions; delicate or slow-to-adapt fish, and anything introduced without established tankmates already wise to the scale-eater's habits, are at real risk of prolonged fin and scale damage. Water should match the general Lake Malawi column — warm, alkaline, well-buffered water in the mid-20s Celsius with a pH on the alkaline side of neutral. This remains a specialist's fish rather than a mainstream community choice, and no formal breeding protocol has been published for it, but it is not the essentially unkept curiosity it might appear from its rarity in the literature.
Conservation
Corematodus taeniatus has not been assessed by the IUCN Red List, and no status should be assumed for it. As a scale-eating specialist restricted to a fairly narrow feeding niche and documented from a limited number of collection points along Lake Malawi's western shore, it is reasonable to assume it occurs at naturally low density — the fate of most specialised, high-trophic-level fish — but this is inference, not a measured population trend. It shares the general pressures facing Lake Malawi's littoral cichlid fauna: inshore habitat disturbance, sedimentation from catchment deforestation, and the broader basin stresses documented across the lake's fisheries and limnology literature. Its true range, abundance and conservation status remain to be formally established.