Taxonomy & naming
The species was described by Kazuhiro Nakaya and Mulimbwa M. Gashagaza in 1995, in the Japanese Journal of Ichthyology (volume 42), under the name it still bears, Neolamprologus longicaudatus — it was placed in Neolamprologus from the outset, not transferred later. The type material was collected on the Zairean (now Congolese) coast of Lake Tanganyika: the holotype (HUMZ 127670) and paratypes came from Cape Banza on the Ubwari Peninsula, in the lake's northwest, taken at about 15 metres depth. The Latin epithet longicaudatus means 'long-tailed', for the species' elongate caudal fin. Eschmeyer's Catalog of Fishes recognises it as a valid species, Neolamprologus longicaudatus Nakaya & Gashagaza 1995, a placement supported by Büscher (1997), Schelly and colleagues (2003) and Konings (2015, 2019). It belongs to the large, ecologically diverse genus Neolamprologus, the dominant lamprologine radiation of Lake Tanganyika, and sits among the slender, rock- and cave-associated members of that genus alongside relatives such as Neolamprologus buescheri and Neolamprologus cylindricus.
Morphology
Neolamprologus longicaudatus is a small to medium lamprologine reaching about 3.5 in standard length, with an elongate, somewhat cylindrical body well suited to threading among rocks. The defining feature is the long caudal fin from which it takes its name. Meristic counts from the original description are 20 dorsal-fin spines with 9–10 soft rays, 5–6 anal-fin spines with 7 soft rays, and 34 vertebrae — a high spine count typical of the rock-dwelling lamprologines. The body shape is described as elongated. In life the fish shows the muted, cryptic patterning of a rock-dweller, with longitudinal striping and dark markings that break up its outline against the boulder field; it broadly resembles the closely comparable Neolamprologus buescheri, with which it shares its habitat and from which it is told apart partly by its more open, less strictly crevice-bound behaviour and by morphometric details. Sexual dimorphism is not strongly documented for the species in the literature, beyond the general lamprologine tendency for males to grow somewhat larger and to develop more extended fin tips.
Habitat
The species is endemic to Lake Tanganyika, recorded from the northwestern shore between the Ubwari Peninsula and the Kavalla Islands in the Democratic Republic of the Congo — a relatively restricted range along the lake's Congolese coast, within the Lake Tanganyika freshwater ecoregion (FEOW 521). It is a fish of the rocky habitat at moderate depth: FishBase gives a depth range of about 12–15 metres, and the original collection was made at around 15 metres. This places it in the mid-depth boulder zone, below the surge-swept shallows but well above the lake's anoxic deep water. As with the rest of the Tanganyikan rock fauna, the water is warm, hard and strongly alkaline (broadly 75–81 °F, pH around 8–9, high carbonate hardness) and well oxygenated. Within the rocky habitat the fish is noted as occurring more often in the open, away from the caves, than its close relative Neolamprologus buescheri, which is more tightly tied to crevices — a subtle habitat partitioning between the two.
Feeding
Neolamprologus longicaudatus is a micro-carnivore of the rocky zone. The published field notes report that it feeds on invertebrates, and its model-estimated trophic level of about 3.6 is consistent with a small predator on invertebrate prey rather than a herbivore. In practice this means picking small crustaceans, insect larvae and other invertebrates from the rock surfaces, crevices and the water immediately around them. Its tendency to be seen out in the open more than the cave-bound Neolamprologus buescheri suggests it forages somewhat more actively over the rock field and the adjacent water column, taking prey that it hunts down rather than only ambushing from a crevice. As a solitary species it does this alone rather than in foraging groups, working its patch of the boulder slope.
Mating
Specific reproductive observations for Neolamprologus longicaudatus are limited, but its biology points to the cave-spawning pattern typical of the rock-dwelling Neolamprologus rather than the harem-of-shells system of the sand-dwellers. The fish is reported to be most often solitary, which is consistent with a pair-forming, cave-based breeder in which individuals hold and defend rock territories and come together to spawn. By analogy with its close relative Neolamprologus buescheri and the other slender rock-lamprologines, a male and female would establish a bond at a chosen crevice or small cave among the boulders, clean a spawning surface within it, and defend the site. The species' affinity for the open rock rather than deep caves may shape the details of its territoriality, but the absence of detailed field breeding studies means the finer points of its courtship and pair behaviour remain to be documented.
Breeding
Neolamprologus longicaudatus is, on the available evidence, a substrate cave-brooder in the manner of the rock-dwelling lamprologines: a female lays adhesive eggs on the wall or ceiling of a rock crevice or small cave, the eggs are fertilised and then guarded and fanned within the shelter, and both parents — or at least the female closely, with the male defending the wider territory — care for the eggs, wrigglers and free-swimming fry. No species-specific clutch counts, egg descriptions or developmental timings have been published; the fish has not been the subject of a dedicated breeding study and is little known in captivity. The expected pattern, drawn from well-studied relatives such as Neolamprologus buescheri, is of modest clutches of a few dozen to a hundred or so eggs, extended biparental guarding of the brood within and around the cave, and fry that shelter in the rockwork. These details should be read as the lamprologine norm applied to this species rather than as confirmed observations of Neolamprologus longicaudatus itself.
In the aquarium
Neolamprologus longicaudatus is only occasionally available in the hobby and is far less familiar than the popular rock-dwellers like Neolamprologus buescheri, Neolamprologus leleupi or Neolamprologus cylindricus, but it is kept on the same principles. It needs a Tanganyika rock-biotope: plenty of stacked rockwork forming caves and crevices, over a sand base, in a tank with enough footprint for the fish to establish a territory — for a pair, on the order of 25 US gal or more, with more space if kept with others.
Water must match the lake: temperature about 75–81 °F, pH roughly 8–9, hard and alkaline, kept clean and well oxygenated with regular partial water changes, since these rock-dwellers are intolerant of declining water quality.
Feeding is straightforward for an invertebrate-eater: small live and frozen foods (brine shrimp, mysis, cyclops, chopped bloodworm) and a quality pellet or flake suit it well. Behaviourally it is a typical slender rock-lamprologine — territorial around its chosen cave but not a large or especially destructive fish, and best given tankmates that occupy other niches (open-water Cyprichromis, sand-sifters, or differently sized rock-dwellers) to avoid direct competition for the same crevices. Because firsthand husbandry accounts are scarce, much of the guidance for it is extrapolated from its close relatives; a keeper should expect a shy, rock-oriented fish that does best in a quiet, well-structured biotope tank.
Conservation
The IUCN Red List assesses Neolamprologus longicaudatus as Least Concern (assessed 28 February 2025; Red List 2025-2). Although its known range — the northwestern Congolese shore between the Ubwari Peninsula and the Kavalla Islands — is relatively restricted, the Least Concern rating reflects the absence of evidence for significant decline and the fact that its rocky mid-depth habitat is not under acute, species-specific threat. The general pressures on the Tanganyikan littoral apply here as elsewhere: shoreline sedimentation from catchment deforestation and erosion, pollution, and the effects of fishing, all of which can degrade inshore rocky habitat over time. None is currently judged to threaten this species at the population level. It carries no CITES listing and is of negligible importance to fisheries, appearing only sporadically and in small numbers in the aquarium trade. As with many narrowly distributed Tanganyikan rock cichlids, continued monitoring of its limited range is the sensible precaution, even under a Least Concern listing.