Taxonomy & naming
Diplotaxodon sp. "Brevimanus" has no describing author, no year of publication, and no FishBase entry, since it has never been the subject of a published taxonomic description. It is known only by an informal field/trade name following the standard open-nomenclature convention for undescribed Malawi cichlids: the genus Diplotaxodon, the abbreviation "sp.", and a descriptive qualifier. "Brevimanus" combines Latin brevis (short) with manus (hand), a construction used informally in fish nomenclature to flag unusually short paired fins; among the characters used to separate the genus's many silvery, large-eyed species, relative fin length and proportion is one that has appeared in taxonomic keys for the group, most notably George Turner's 1994 revision work on Diplotaxodon. No formal description or revision covering this specific form exists, and its precise relationship to the genus's described species has not been resolved.
Morphology
This form follows the standard Diplotaxodon body plan: an elongate, laterally compressed, torpedo-shaped fish built for sustained open-water swimming rather than the deep-bodied profile typical of rock-dwelling Malawi cichlids, with the large eyes characteristic of the genus, an adaptation for gathering light in the dim, blue-shifted water many Diplotaxodon species inhabit. The trade name implies comparatively short pectoral or pelvic fins relative to other Diplotaxodon, though the specific measurement has not been published for this form. Genus-typical size runs roughly 4–6 in SL; no species-specific measurements are documented here.
Habitat
Diplotaxodon sp. "Brevimanus" is recorded from open water off Nkhata Bay, a well documented Diplotaxodon collecting area on Lake Malawi's Malawian shore. Unlike the mbuna and utaka that dominate the lake's rocky and sandy littoral, Diplotaxodon does not associate with any substrate at all — it is a pelagic fish, living in loose schools over open, often deep water well offshore. The genus as a whole spans a wide depth envelope, from moderate depths down into the dim, cool waters of the lake's deep mixed and transition layers, and many species undertake a nightly vertical migration toward the surface to feed before retreating to depth by day. Surface water follows Lake Malawi's standard chemistry — warm, hard, and alkaline — though the deeper water this genus favours runs cooler and less oxygenated.
Feeding
Diplotaxodon as a genus is built around zooplanktivory: the fish forage in open water for copepods, cladocerans, and other zooplankton, picking individual prey items from the water column rather than grazing a substrate or sifting sediment. Several species are known to feed near the surface at night, coinciding with their vertical migration. No dedicated dietary study exists for "Brevimanus" specifically, so its diet is presented here as genus-typical zooplanktivory rather than a documented fact for this exact form.
Mating
Reproductive behaviour in Diplotaxodon is poorly documented for the genus as a whole, and essentially undescribed for this particular form. Pelagic living makes courtship and spawning difficult to observe directly, since the fish do not hold conventional rock or sand territories the way most Lake Malawi cichlids do. What social structure has been inferred for the genus points to open-water, likely lek-like breeding rather than fixed pair bonds, consistent with the maternal mouthbrooding shared across every Malawi haplochromine, but the specific courtship sequence, territory type, and timing for this form have not been recorded in the literature available here.
Breeding
As with every Lake Malawi cichlid, Diplotaxodon sp. "Brevimanus" is presumed to be a maternal mouthbrooder: the female takes fertilised eggs into her mouth and carries the developing brood there until the fry are free-swimming. Diplotaxodon is notable within the lake's cichlid fauna for unusually low fecundity in the species studied in any detail — broods of only a handful of well-developed, comparatively large fry rather than the dozens typical of rock-dwelling mbuna. Whether that pattern holds for this specific form has not been confirmed; it is presented here as a genus-typical expectation, not a documented count.
In the aquarium
Diplotaxodon sp. "Brevimanus" is not an established aquarium fish. Pelagic Diplotaxodon species are collected far less often than rock and sand cichlids, are more delicate in transport, and require the kind of large, open, well-oxygenated midwater space that few home aquaria can provide; the genus is essentially absent from the ordinary hobby trade. Any keeper who did encounter this form would need to approach it as a schooling open-water fish rather than a territorial cichlid — a large, uncluttered tank, strong water movement and oxygenation, and the standard hard, alkaline Lake Malawi water chemistry (roughly 75–82 °F, pH 7.7–8.6 or a little higher) — but specific husbandry experience with this form has not been documented and none should be invented.
Conservation
Diplotaxodon sp. "Brevimanus" has no IUCN Red List assessment, since formal evaluation requires a validly published scientific name and this form has never received one. More broadly, Lake Malawi's pelagic Diplotaxodon community is exposed to pressures distinct from the inshore rock-dwellers: it overlaps with the open-water usipa (Engraulicypris sardella) and utaka fisheries, which use fine-mesh nets capable of taking cichlids as bycatch, and the genus's dependence on deep, cool, well-oxygenated water makes it potentially sensitive to the lake's documented warming and strengthening thermal stratification, which reduces the mixing that resupplies oxygen to deeper layers. No population-level data exist for this specific form to say more than that it shares those general exposures.