Taxonomy & naming
Lamprologus teugelsi was described in 2004 by Robert C. Schelly and Melanie L. J. Stiassny of the American Museum of Natural History, in their revision of the Congo River Lamprologus (American Museum Novitates 3451). It was one of two new species erected in that paper — the other being Lamprologus tigripictilis — and was distinguished from its congeners on the basis of counts, measurements, osteology, and colour pattern. The species was described directly in Lamprologus, so that name is also its original combination; there are no synonyms.
The genus Lamprologus itself has a tangled history. Erected by the Dutch zoologist Louise Schilthuis in 1891 for Lamprologus congoensis from the Congo's Stanley Pool, it became, through the twentieth century, a dumping ground for dozens of Lake Tanganyika lamprologines — at one point more than fifty nominal species. Successive workers (Colombé & Allgayer 1985, Poll 1986) split most of those off into Neolamprologus, Lepidiolamprologus, Altolamprologus and other genera, and Stiassny (1997) showed that Lamprologus sensu stricto should be restricted to the riverine species of the Congo basin. By that definition the genus today holds nine species, all Congo endemics; Lamprologus teugelsi is among the most recently named, joined later by Lamprologus markerti (2014). The species belongs to the tribe Lamprologini within the African cichlid subfamily Pseudocrenilabrinae, and Schelly & Stiassny tentatively recovered the Congo River Lamprologus as a monophyletic group within it.
The type material was collected in the lower Congo, and the species is named in memory of Dr Guy G. Teugels (1954–2003), the Belgian ichthyologist and curator of fishes at the Musée Royal de l'Afrique Centrale in Tervuren, honoured for his leadership in African ichthyology and his support of African students of the science.
Morphology
Lamprologus teugelsi is a small cichlid, reaching about 3 in in standard length. It is among the more robustly built members of the genus — Schelly & Stiassny describe it as a relatively stout, deep-bodied species, especially in adults, in contrast to the more elongate, torpedo-shaped congeners like Lamprologus congoensis. The head is moderate (roughly 31 to 34 percent of standard length), the jaws roughly even with the lower lip sometimes protruding slightly, and both the outer and inner tooth rows are made up of sharp, single-cusped (unicuspid) teeth. Fin counts run to 17–19 dorsal spines with 8–9 soft rays, and 5–6 anal spines with 6–7 soft rays; the spines lengthen gradually toward the rear of each fin, and the last soft rays of the dorsal and anal draw out into filaments that trail past the base of the tail. The caudal fin is moderately large and rounded — never the paddle-shaped or pointed tail seen in some relatives.
Colour is the easiest field mark. The ground colour is a light grey crossed by six broad, irregular dark bars separated by thinner whitish blotches; the dorsal, anal and caudal fins are darkly pigmented, the dorsal edged in pale yellow and the upper edge of the tail tinged reddish. Most diagnostic is the scale pattern: each flank scale carries dark pigment along its exposed rear margin, and because the scales overlap in regular rows, the dark edges line up into intersecting oblique bands that give the fish the look of chain-link fencing or chain-mail. Like other Lamprologus, males grow somewhat larger than females and develop a more pronounced nuchal hump on the forehead; breeding fish, particularly females, darken markedly, sometimes to nearly black.
Habitat
The species is a narrow-range Congo-basin endemic, recorded only from Malebo Pool (the former Stanley Pool, the broad lake-like widening of the river just above Kinshasa) and from the lower Congo River rapids downstream toward Inga, all within the Democratic Republic of the Congo. In the language of freshwater biogeography it spans two ecoregions — the Malebo Pool and the Lower Congo Rapids — and like its congeners exhibits a narrow, parapatric distribution within the basin, with collection records leaving large gaps that hint at how incompletely this fauna has been sampled.
The Lower Congo Rapids are among the most extreme freshwater habitats on the planet: in roughly 217 mi between the foot of Malebo Pool and Matadi the river drops about 919 ft through dozens of cataracts, generating some of the strongest currents and most turbulent, oxygen-rich flows of any river. Riverine Lamprologus are rheophilic — adapted to fast water — and have reduced swim bladders that help them stay pinned to the bottom in the current; they shelter among rocks and in crevices on hard, rocky substrate. Lamprologus teugelsi also extends up into Malebo Pool, a quieter, more lake-like setting with sandy and silted bottoms, so the species bridges both the white-water cataract and the calmer pool. The water of this lower-Congo reach is warm and often heavily turbid; in the rockier stretches visibility can fall to a few centimetres. As a soft-water tropical river fish, it lives in warm conditions broadly in the range of about 75–82 °F and near-neutral, soft chemistry, though precise in-situ measurements for this particular species are not published.
Feeding
Riverine Lamprologus are insectivores, and Lamprologus teugelsi fits the pattern. The genus has short, simple intestines typical of an animal-based diet, and these fish forage over and among rocks for aquatic insect larvae and other small invertebrates carried or sheltered in the current. FishBase places the species at a trophic level near 3.8, consistent with a small predatory invertivore rather than a herbivore or detritivore. No detailed gut-content study has been published for Lamprologus teugelsi specifically, so its diet is inferred from the well-documented feeding habits of the genus as a whole; within the lower-Congo community it functions as one of many small benthic insectivorous cichlids working the rocky substrate alongside Steatocranus, Teleogramma, Nanochromis and others.
Mating
Reproductive behaviour has not been observed in the wild for any riverine Lamprologus, and Lamprologus teugelsi is no exception; what is known comes from aquarium observation of the genus. These cichlids form stable, monogamous pairs and are cave brooders. Pair members keep close company but characteristically do not share a single cave or hiding place, instead holding adjacent shelters within a defended territory. As spawning approaches the fish intensify in colour, with both sexes — especially the female — darkening, sometimes to almost solid black. Males, the larger sex with the bigger forehead hump, hold and defend the broader territory, and courtship leads the pair to a chosen rocky cavity in which the eggs will be laid. Given the species' preference for hard, rock-strewn substrate in fast water, natural spawning sites are presumed to be crevices and cavities among the rocks of the rapids.
Breeding
Breeding has not been documented in the wild; the account here is drawn from the reproductive biology of the riverine Lamprologus in captivity, which is consistent across the genus and very likely applies to Lamprologus teugelsi. These fish are monogamous cave spawners. The female attaches a clutch of small, whitish eggs to the roof or wall of the chosen cavity — large females of the genus may lay up to roughly 400 eggs — and tends them largely on her own, fanning and guarding inside the cave while the male defends the surrounding territory. Eggs hatch after about three days, and the wrigglers, which carry cryptic substrate-matching coloration, remain in the cave until they have absorbed their yolk sacs, becoming free-swimming roughly six to seven days after hatching. For the first week or so of free swimming the pair actively guard the fry; thereafter the parents shift toward defending the territory and tolerating the young within it rather than herding them closely, and the juveniles gradually disperse and leave over the following four to six weeks. Exact clutch sizes, egg dimensions and developmental timing for Lamprologus teugelsi itself have not been published.
In the aquarium
Lamprologus teugelsi is essentially a fish for specialist keepers of Congo riverine cichlids, and it appears in the hobby only sporadically; several of its congeners are better established in the trade. Where the genus is kept, the husbandry principles are well understood and would apply directly to this species.
These are active, fast-moving rheophilic cichlids, so a tank of at least about 30 US gal is a sensible minimum for a pair, with more space strongly preferred for a group or for breeding. Because the fish come from some of the most turbulent, oxygen-saturated water on Earth, strong circulation, vigorous oxygenation and frequent water changes matter far more than precise chemistry. The aquascape should mirror the rocky rapids and sandy pool the species inhabits: a sand substrate with a generous arrangement of rockwork forming natural caves and crevices, ideally supplemented with waterlogged wood; aquatic plants are not part of the natural habitat and are not needed. The caves are not decorative — without secure rocky retreats the fish will neither settle nor spawn.
Wild Lamprologus water is soft, but the genus is hardy and adaptable, and water chemistry is a secondary concern provided it is clean and well oxygenated. A temperature in the mid-20s °C (roughly 75–79 °F) and a pH around neutral suit them, and they tolerate a range on either side of that; soft, slightly acidic water of about pH 6.5–7.0 is a reasonable target for breeding attempts. Feeding is straightforward for an insectivore: small live and frozen invertebrate foods are taken eagerly and good-quality prepared foods are accepted. The fry, though tiny, are easy to raise on baby brine shrimp, microworms and similar first foods.
The main pitfalls are behavioural and environmental rather than dietary. As territorial cave brooders the fish need enough space and structure that a pair can hold a territory without being harassed; they should not be housed with large, boisterous cichlids that will dominate the tank and prevent them from establishing. Neglecting flow and oxygenation, or trying to keep them in a still, plant-choked community tank, works against everything their biology is built for. With a current-rich, rock-and-sand setup and stable, well-oxygenated water, the keepable riverine Lamprologus have proven both manageable and willing to breed.
Conservation
The IUCN Red List assesses Lamprologus teugelsi as Vulnerable under criterion D2 (assessed 16 February 2009 by T. Moelants, published 2010), a category reserved for species with a very restricted range that could be pushed toward extinction by a single plausible threat over a short period. The assessment treats the fish as endemic to the Democratic Republic of the Congo, with its population trend listed as unknown, and identifies dam construction and water management on the Congo as the principal threat. That concern is concrete: the species' range coincides with the Inga rapids reach of the lower Congo, the site of existing hydropower dams and of the long-proposed Grand Inga mega-dam scheme, any major expansion of which would alter the very cataract flows the species depends on.
More broadly, the lower Congo River and Malebo Pool sit within a stretch of river of exceptional and still poorly catalogued fish diversity, much of it made up of narrow-range endemics adapted to specific hydraulic micro-habitats — exactly the kind of fauna most exposed to flow alteration, pollution, and the gaps in survey effort that leave many populations essentially unmonitored. Lamprologus teugelsi has no CITES listing and is not a fishery target of note, but its small range and dependence on a single, dam-threatened river system are the reasons it is flagged as Vulnerable rather than of Least Concern.