Taxonomy & naming
Neolamprologus cylindricus was described by Wolfgang Staeck and Lothar Seegers in 1986, in the German aquarium journal Die Aquarien- und Terrarienzeitschrift (DATZ), from specimens collected just south of the mouth of the Kalambo River on the Zambian shore (the holotype, ZFMK 14595, is held in Bonn). Eschmeyer's Catalog of Fishes lists the name as valid and the species has carried it without controversy since; this is a stable taxon, not one of the lamprologine names shuffled between genera in recent revisions.
The species belongs to the large, exclusively Tanganyikan genus Neolamprologus, part of the substrate-brooding "lamprologine" tribe (Lamprologini) that has radiated into rock-dwellers, sand-dwellers and the famous shell-dwellers of the lake. The genus name blends Greek roots — neos (new) with the older genus Lamprologus (from lampros, "torch," and lagos, "hare") — while the epithet cylindricus simply describes the animal's notably tubular, cylindrical body. In the hobby it is usually sold plainly as the "cylindricus," occasionally as the "cylindricus cichlid."
Morphology
This is a slender, almost torpedo-shaped fish: a long, round-bodied lamprologine without the deep flanks of an Altolamprologus or the high back of a Julidochromis. The signature feature is the patterning — a series of seven to nine dark vertical bars, usually deep brown to black, stacked along a pale grey-to-cream ground, often with a faint bluish or violet sheen on the unpaired fins and lyre-tipped tail. The contrast is clean and high, which is what gives the fish its display-case appeal.
Maximum size is a point where careful sources and care sheets diverge. FishBase records a maximum of about 4.1 in (4 in) total length, and Konings' field measurements put wild fish at roughly that ceiling; many hobby pages, however, quote 5 in (5 in) or more, likely reflecting well-fed aquarium specimens or generous rounding. A realistic expectation is around 3.5–4 in (3.5–4 in) for males, with females noticeably smaller. Sexual dimorphism is otherwise subtle: mature males tend to be larger with slightly more produced dorsal and anal fin tips, and ripe females show a rounder belly, but venting a suspected pair remains the only reliable way to sex them. The bold barring can be confused with other striped lamprologines such as Neolamprologus buescheri or barred Julidochromis, but the distinctly cylindrical profile and even, body-wide bars are diagnostic.
Habitat
Neolamprologus cylindricus is a Lake Tanganyika endemic with a restricted range: it occurs only along the southeastern coast, recorded from around Karema on the Tanzanian side south to the Nkumbula Island area near the lake's southern tip in Zambia (Konings 1998; Aibara et al. 2005). This is a single-lake, single-sector distribution — it is found nowhere else on Earth.
Within that range it is a shallow rocky-shore specialist. Ad Konings' in-situ observations place it in the upper roughly 33 ft of the rocky biotope, and the IUCN assessment gives a depth band of 0–33 ft. Rather than hovering in open water, the fish lives down inside the structure, threading through the recesses, cracks and shaded undercuts between boulders. Its water is the hard, alkaline, exceptionally stable medium of Tanganyika: FishBase cites a pH range of about 7.0–8.5 and temperatures of 73–82 °F (73–82°F), though the open lake typically sits nearer pH 8.5–9.0. That preference for warm, oxygen-rich, highly buffered water over a rocky substrate is the single most important thing to understand about keeping it.
Feeding
In the wild Neolamprologus cylindricus is a micro-carnivore — a small ambush and gleaning predator of the rock face. Konings reports that it feeds on invertebrates such as shrimps and other crustaceans taken from the biocover (the algal-and-detritus film on the rocks) and from inside the recesses of the substrate; FishBase places it at a trophic level of about 3.5. Some hobby accounts add small fish and fry to the menu, which is plausible for an opportunistic crevice hunter of this size, though the documented diet is dominated by invertebrates.
Ecologically it fills the role of a small, solitary rock-dweller, one of dozens of cichlid species partitioning the littoral zone of the lake by depth, substrate and feeding style. FishBase explicitly describes it as solitary, which fits its behavior: an individual holds and patrols a short section of reef rather than schooling. That makes it a minor but characteristic predator in the dense, intensely territorial community of the rocky shallows.
Mating
Neolamprologus cylindricus is a cave-spawning substrate brooder, not a mouthbrooder — a crucial distinction from the Tanganyikan mouthbrooders it often shares a tank with. A pair adopts a crevice or small cave and the female tends the eggs and wrigglers deep inside while the male patrols and defends the surrounding territory.
The behavioral headline is aggression. This is a genuinely territorial fish, and keepers across forums consistently warn that it turns nasty toward its own kind and toward similarly shaped, similarly striped lamprologines — agreement strong enough to state as fact rather than anecdote. Two main approaches recur in the community: keep a single proven pair, or start with a small group in a large, heavily structured tank and let a pair form, removing surplus fish as the hierarchy sorts itself out (the same colony-thinning logic experienced Tanganyika keepers apply to many lamprologines). Once a pair spawns, hostility escalates sharply, and a spawning pair can make a modest tank untenable for anything sharing their rock pile.
Breeding
Spawning takes place on the inner surface of a chosen crevice or cave. FishBase notes the species raises fry "in seclusion," which matches the secretive, hole-based strategy. The female assumes primary responsibility for egg and larval care within the cavity while the male maintains an outer defensive perimeter around the spawning site.
Reported figures from keepers cluster around eggs hatching in roughly two to three days at about 79 °F (79°F), with fry free-swimming a few days later and taking newly hatched brine shrimp and fine foods; treat the exact timings as the soft, temperature-dependent numbers they are. Once the fry are free-swimming, both parents actively defend them. The biparental division of labor — female inside tending brood, male outside holding territory — is characteristic of the genus and should be accommodated in any breeding setup by providing a cave mouth wide enough for the female but backed by a deep enough recess to give her separation from the male when she needs it.
In the aquarium
For an advanced beginner to intermediate keeper, cylindricus is one of the more rewarding small Tanganyikans: hardy, long-lived (a decade is reasonable with good care), strikingly marked, and willing to breed. The non-negotiables are hard, alkaline water (pH roughly 8.0–9.0, high carbonate hardness), warm temperatures around 75–82°F (75–82 °F), strong oxygenation and filtration, and a scape built from real rockwork forming tight caves and broken sightlines over a sandy bottom. A pair can be housed in a tank of around 4 ft / 55 US gal; a community of mixed Tanganyikans needs considerably more length so territories don't overlap.
The most common mistakes are stocking-and-aggression mistakes. Crowding two or more cylindricus into a small tank, or pairing them with look-alike barred lamprologines, reliably produces bloodshed. Better tankmates occupy different niches: Altolamprologus calvus and compressiceps, small Julidochromis, midwater dither shoals like Cyprichromis, and shell-dwellers (Neolamprologus multifasciatus, similis) given their own segregated sand zone. Avoid timid or slow species and anything that competes for the same rock crevices. Feed a protein-forward diet — quality carnivore pellets plus frozen mysis, brine shrimp and the like — and keep nitrate down with routine water changes. Diet note: skip mammalian meats and don't lean on feeder fish.
Conservation
Neolamprologus cylindricus was assessed by the IUCN as Least Concern in 2025 (assessment by Fermon; published 2025, version 2025-2). The reasoning is straightforward: although it is endemic to a single sector of one lake, it is widely and continuously distributed along the southeastern coast, and no major, widespread threat specific to it has been identified. The assessment does flag minor, ongoing pressures — small-scale subsistence fishing and agricultural/forestry pollution — and notes the species enters the aquarium trade (collected nationally and exported), but neither rises to a population-level concern, and there are currently no species-specific conservation actions or protected areas covering it. Its population trend is simply unknown.
That "Least Concern" verdict should be read against a lake under real strain. Lake Tanganyika is warming, and the warming has consequences that reach the bottom of the food web: O'Reilly et al. (2003, Nature, doi:10.1038/nature01833) inferred from sediment records that rising temperatures have strengthened stratification and reduced mixing, cutting primary productivity by roughly 20% and implying on the order of a 30% drop in fish yields. Cohen et al. (2016, PNAS, doi:10.1073/pnas.1603237113) used paleoecological cores to show that warming since the 19th century has been accompanied by declines in commercial fishes and endemic molluscs and an estimated ~38% loss of the lake's oxygenated benthic habitat as the oxygen-bearing surface layer thins. Layered onto this are shoreline pressures — sedimentation and nutrient runoff from deforestation degrading the very rocky littoral where this fish lives (Cohen et al. 1993) — while a four-nation pelagic fishery built on the clupeids Stolothrissa and Limnothrissa and the predatory Lates feeds millions of people, with management coordinated across Burundi, the DRC, Tanzania and Zambia through the Lake Tanganyika Authority. For a shallow rocky-shore endemic like cylindricus, the most direct of these threats is sedimentation smothering the crevice habitat it depends on, with warming-driven productivity loss a slower, basin-wide backdrop. The honest summary: the species itself is not currently threatened, but its home is changing, and a fish confined to ten metres of one shoreline has little room to move if that shoreline degrades.