Taxonomy & naming
Teleogramma depressa was described in 1976 by the American ichthyologists Tyson R. Roberts and Donald J. Stewart in their landmark monograph 'An ecological and systematic survey of fishes in the rapids of the lower Zaire or Congo River' (Bulletin of the Museum of Comparative Zoology, vol. 147). They originally coined the name as Teleogramma depressum, treating the genus as neuter; the Catalog of Fishes notes that the genus Teleogramma is in fact feminine, so the grammatically correct combination is Teleogramma depressa, the spelling now in use (Stiassny & Alter, 2015). The holotype (MCZ 50482) and an extensive paratype series are held at the Museum of Comparative Zoology, with material distributed to the BMNH, MRAC, and USNM; the type locality is the lower Congo River near the Inga rapids in the Democratic Republic of the Congo (about 5°27.5'S, 13°36.0'E). The genus Teleogramma was erected by George Albert Boulenger in 1899. Roberts and Stewart recognized four species; for decades three of them — Teleogramma depressa, Teleogramma brichardi, and Teleogramma gracile — were considered endemic to outcrops along the lower Congo, with Teleogramma monogramma occurring far upstream near the Kasai–Lulua confluence. A molecular and morphological revision by Stiassny and Alter (American Museum Novitates 3831, 2015) added a fifth species, Teleogramma obamaorum, and showed that the lower-Congo populations form a tight cluster of very young, short-branched lineages — so recently and rapidly diverged that morphology-based taxonomy and the genetic signal are in partial conflict. Within the African cichlid subfamily Pseudocrenilabrinae, Teleogramma belongs to the chromidotilapiine assemblage, a lineage whose divergence long predates the explosive lacustrine radiations of the eastern African Rift lakes.
Morphology
Teleogramma depressa is a small cichlid; FishBase records a maximum of about 3.5 in standard length, and like all members of the genus it rarely tops 4 in. The body plan is the genus's signature: an elongate, laterally compressed trunk set behind a markedly dorsoventrally flattened head — the trait that gives depressa its name — bearing a pair of prominent tubular nostrils. A single, continuous lateral line runs the length of the flank, undivided into the upper and lower branches seen in most cichlids; this uninterrupted 'complete line' is what inspired Boulenger's genus name. The fins are reduced and the overall silhouette is low and streamlined, an obvious adaptation to gripping the bottom in fast water. Coloration is generally dark — smoky grey to grey-black above, fading paler below — matching the shadowed rock interstices the fish inhabits in turbid, humic-stained water. The species is strongly sexually dimorphic, in the manner Roberts and Stewart documented across the genus: females develop a distinctively marked caudal fin with a contrasting dorsal 'blaze,' and ripe females flush a pronounced red on the belly, a dichromatism shared with other Teleogramma and many chromidotilapiine cichlids. Males lack the caudal blaze and tend to be the larger, plainer sex. These visual signals, set against an otherwise cryptic dark body, are the readiest way to tell the sexes apart.
Habitat
Teleogramma depressa is endemic to the lower Congo River, the final roughly 320-kilometre (200-mile) stretch where the river drops off the central African plateau toward the Atlantic below Pool Malebo (Stanley Pool). This is the most powerful stretch of river on the planet: exceptionally deep — in places several hundred metres — and broken into a chaos of rapids, standing waves, whirlpools, and deep canyons whose hydraulic forces are extreme. The species occurs on both banks, in the Democratic Republic of the Congo and the Republic of the Congo, and recorded localities span the channel from near Kinshasa down past Luozi, Kinganga, and the Inga rapids near the type locality. It is a demersal, rheophilic fish, living among and within rock outcrops and crevices in or beside the main channel — habitats that for much of the year lie submerged well below the surface and were sampled in detail only during the exceptionally low water of 2011. The water is warm, soft, and turbid: the lower and middle Congo carry a heavy sediment load and intense humic staining washed down from the upstream Cuvette Centrale, and Stiassny's team observed that light attenuates rapidly, fading to near-darkness between roughly 0.5 and 3 ft below the surface. The river is broadly soft and circumneutral. No fine-scale in-situ chemistry has been published specifically for this species; values cited for husbandry below are inferred from the genus and the general character of lower-Congo rapids water.
Feeding
Teleogramma depressa is an insectivore that forages over and within rock surfaces in the current. Examination of gut contents across the genus by Stiassny and Alter (2015) found that the rapids-dwelling congeners — the group that includes Teleogramma depressa — feed almost exclusively on aquatic insect larvae and nymphs, predominantly mayflies (Ephemeroptera) and, to a lesser degree, caddisflies (Trichoptera), stoneflies (Plecoptera), and chironomid midges, picked from rock surfaces and prised out of interstices. This is the ancestral trophic mode of the genus; only the snail-eating Teleogramma obamaorum, with its enlarged pharyngeal jaws, departs from it. FishBase places Teleogramma depressa at a trophic level near 3.3, consistent with a small benthic predator of invertebrates. Its flattened, bottom-hugging body and reduced fins suit a fish that works the substrate in turbulent flow rather than feeding in open water, and in the rapids community it occupies the niche of a crevice-foraging insectivore alongside the many other endemic fishes of these channels.
Mating
Direct field observations of courtship in Teleogramma depressa are scant, but the social biology can be read from its morphology, its congeners, and the broader chromidotilapiine lineage to which the genus belongs. The strong sexual dichromatism — the female's blazed caudal fin and red belly flush versus the plainer male — points to active, sex-specific signaling during pair formation, with the brightening female advertising readiness rather than the male, a pattern typical of dwarf chromidotilapiines. FishBase characterizes the species as pair-bonding. In the confined, turbulent crevice habitat these fish occupy, a breeding pair almost certainly holds and defends a rock cavity as a territory, the female's heightened coloration mediating courtship at close range in dim, fast water. The recency of divergence among the lower-Congo Teleogramma, and evidence that the rapids themselves act as barriers limiting gene flow between populations only a kilometre or two apart (Alter et al., 2017), implies that pairs form and reproduce within these tightly bounded local 'neighborhoods' rather than across the wider river.
Breeding
Teleogramma depressa is a cave spawner with biparental pair-bonding, the reproductive mode FishBase assigns it and the one characteristic of the genus and its chromidotilapiine relatives. Eggs are laid on the wall or ceiling of a rock cavity or crevice and guarded by the parents until the fry are free-swimming and shepherded by the pair — the standard chromidotilapiine cave-brooding template seen across related lower-Congo and west-African cichlids. No clutch count has been published specifically for Teleogramma depressa; by comparison with similarly sized cave-spawning chromidotilapiines, clutches are expected to be modest, on the order of a few dozen to perhaps roughly a hundred eggs, rather than the large open-water spawns of substrate-brooding cichlids. The female's pronounced red belly and blazed tail in breeding condition almost certainly function in the close-quarters courtship and pair coordination that precede spawning. The cave-spawning habit is itself an adaptation to the environment: sealing eggs and larvae inside a rock cavity shelters the brood from both predators and the scouring force of the current. Detailed accounts of egg number, incubation time, and fry development in this particular species remain undocumented in the published literature.
In the aquarium
Teleogramma depressa is, at best, a rarely kept specialist's fish and effectively absent from the general hobby; far more aquarium experience exists with its better-known relative Teleogramma brichardi, and most husbandry guidance for depressa is extrapolated from that congener and from the demands of its wild habitat. It is not a beginner's species. The defining requirement is flow and oxygen: these are fish of the world's most turbulent river, and a tank must reproduce strong, well-oxygenated current — powerheads or a river-manifold setup — over a hardscape of rounded rocks and cobbles arranged to create the narrow horizontal crevices the fish hides and breeds in. Cover is not optional; without tight retreats the fish are stressed and reclusive. Water should be warm and soft, roughly 75–82 °F, with a pH near neutral (about 6.5-7.5) and low to moderate hardness, matching the soft, circumneutral character of lower-Congo water; pristine, well-filtered conditions and steady oxygenation matter more than chasing exact numbers. Diet is small live and frozen invertebrate fare — bloodworm, blackworm, mysis, and similar — reflecting the wild insectivorous habit; many specimens are slow to take dry foods. Teleogramma are intolerant of their own kind outside a bonded pair: males in particular are aggressive toward conspecifics, and a single pair in a roomy, rock-divided tank with plenty of broken sightlines is the realistic stocking. Suitable tankmates are other robust, current-loving lower-Congo or West African fishes that occupy different niches; small or timid surface fish are a poor match for the boisterous, well-oxygenated environment these cichlids need. Captive breeding, when achieved in the genus, follows the cave-spawning pattern, with the pair tending eggs and fry inside a chosen crevice. In short: a demanding, specialist subject best left to keepers prepared to build a true high-flow rapids biotope.
Conservation
The IUCN Red List assesses Teleogramma depressa (as Teleogramma depressum) as Near Threatened, assessed on 16 February 2009 by T. Moelants and published in 2010; the population trend is listed as unknown. The single threat identified is dam construction and water management — a serious concern given that the species' entire range lies along the lower Congo at and around the Inga rapids, the focus of major proposed and existing hydropower development (the Inga dam complex and the long-discussed Grand Inga scheme). Because Teleogramma are restricted to specific rapids and rock outcrops, and because the lower Congo's intense hydraulics act as natural barriers that have split the genus into many narrowly localized, genetically distinct populations (Alter et al., 2017), any large dam that drowns rapids, alters flow, or fragments the channel would strike directly at habitat the fish cannot easily leave or recolonize. Researchers studying the system, including Melanie Stiassny, have warned that such development would interrupt the evolutionary engine that makes the lower Congo — where about a quarter of the fishes are endemic — one of the most distinctive freshwater faunas on Earth. The species carries no CITES listing. Its very small range and the looming, well-documented threat of damming are the central facts of its conservation status.