Taxonomy & naming
Apistogramma uaupesi was described by the Swedish ichthyologist Sven O. Kullander in 1980, in his foundational monograph "A taxonomical study of the genus Apistogramma Regan, with a revision of Brazilian and Peruvian species" (Bonner Zoologische Monographien 14: 1–152), where it appears as an original combination on page 122. The type locality is an affluent of the Rio Uaupés (Vaupés) at Trovão, roughly 12 mi from the river's mouth, at 0°02′N, 67°26′W in Amazonas State, Brazil — coordinates the original description carries and FishBase still reproduces. The species epithet is a toponym for that river, glossed by the ETYFish Project simply as "of the rio Uaupés drainage system." Within the genus — placed in the eartheater tribe Geophagini of the Neotropical cichlids — the Cichlid Room Companion files uaupesi in the iniridae species group, the assemblage of small, slender, sail-finned blackwater Apistogramma that includes Apistogramma iniridae and Apistogramma pertensis; the 2016 description of the related Apistogramma helkeri likewise discusses uaupesi among its near relatives in this broader pertensis lineage.
In the hobby the fish has long circulated under informal labels — "Rotkeil" or "red-wedge" (for the colored patch in the tail) and "red-face" — and it carries the collector code A156. None of these is an established English common name, so the species is best referred to by its binomial. A real taxonomic caution applies here: Apistogramma uaupesi sits among several near-identical forms from the Negro and upper Orinoco, and specimens without a confirmed catch locality often cannot be told apart. The IUCN assessment, following Brazil's national ICMBio review, notes that records attributed to the species from the Orinoco basin and elsewhere may in fact represent an undescribed look-alike.
Morphology
This is a small fish even by Apistogramma standards. FishBase records a maximum of about 1 in standard length for a male and roughly 2.5 in total length for a larger female, while the IUCN account cites average lengths "up to 3 in" (3.1 in) — a discrepancy worth flagging, since most aquarium specimens are well under the upper figure. Either way, expect an adult under 3 in.
The build is long and lean with a notably tall, smooth, sail-like dorsal fin. Males develop a lyrate (lyre-shaped) caudal fin, often marked with a wedge-shaped reddish or coppery patch in its center — the source of the "red-wedge" trade name, though its intensity varies from fish to fish. Dominant males can show electric-blue facial markings and rows of dark abdominal spots; the lateral band waxes and wanes with mood, sometimes collapsing to a single spot or vanishing entirely. Keepers consistently describe the species as exceptionally "expressive," flicking the dorsal between fully folded and full display within seconds. Sexual dimorphism is clear: males are larger, carrying the elongated lyre-tail and taller dorsal, while females are smaller and rounder-finned and, in breeding dress, turn a vivid yellow with sharper black markings. The lyrate tail helps separate males from the rounder-tailed Apistogramma iniridae and Apistogramma pertensis, but reliable species-level identification still leans heavily on knowing where the fish was caught.
Habitat
Apistogramma uaupesi is native to the Rio Uaupés (Vaupés) and the nearby Rio Negro drainage of the upper Amazon basin in Brazil; the IUCN lists its extent of occurrence at about 332,0 mi² spanning Amazonas and Amapá states. Reports from the upper Orinoco in Colombia and Venezuela exist but, as noted above, may belong to similar undescribed species, so the confidently confirmed range is the Brazilian Negro/Uaupés system.
This is classic blackwater country — tea-dark, tannin-stained, nutrient-poor water draining ancient white-sand catchments. The chemistry is extreme: FishBase gives a pH range of 4.0–5.0 and a temperature band of 73–84 °F (73–84 °F), and field collectors report carbonate hardness near zero (under 1 °dGH) with pH readings ranging from about 5.5 down to as low as 3.8. Hobbyist authorities on the group note that pH in this region likely swings considerably over the day but never approaches neutral. These are shallow-water fish: like its leaf-litter congeners, Apistogramma uaupesi keeps to the forested margins and submerged litter banks rather than open channel, a depth band on the order of 0–7 ft (FishBase publishes no numeric depth range, so this is a habitat-typical figure, flagged as such). Within that water it associates above all with submerged leaf litter and overhanging marginal vegetation, and the IUCN account describes apparent upstream movements, classifying the species as a migrant.
Feeding
Like other dwarf Apistogramma, Apistogramma uaupesi is a small benthic micro-predator rather than a specialist of any single food. FishBase estimates its trophic level at about 3.3, consistent with a diet built from tiny invertebrates — aquatic insect larvae, microcrustaceans, worms and other small prey — gleaned from the leaf litter, biofilm and sand of the forest-shaded shallows it favors. The blackwater habitat it occupies is strikingly unproductive: with almost no dissolved minerals and heavy tannin loading, the submerged leaf-litter mat itself is the engine of the local food web, hosting the invertebrate life these cichlids hunt. In community terms the fish is a low-level consumer and, given its size, itself prey for larger characins, pike cichlids and other predators — which helps explain its strong attachment to cover. FishBase rates its fishing vulnerability as low and its resilience as medium.
Mating
Socially Apistogramma uaupesi follows the harem-polygynous pattern typical of the genus: one male holds a broad territory overlapping the smaller territories of several females, courting and spawning with each in turn. The species is territorial and, by the testimony of multiple independent keepers, distinctly quarrelsome toward its own kind — fish will shred one another's fins without enough broken sightlines and hiding places. Several breeders also report that pairs are "picky": simply housing a male and female together often produces no spawning at all, and a mismatched pair may never settle. Courtship is keyed to water chemistry as much as to behavior — a ripe female develops her yellow breeding dress, selects and defends a small cavity and solicits a passing male to it, after which she does essentially all of the brood care while the male patrols the wider territory.
Breeding
Apistogramma uaupesi is a cave-spawning substrate brooder with maternal care — the standard Apistogramma pattern, and one FishBase records explicitly for this species: the eggs are attached to the ceiling of a cave and the female cares for the eggs and larvae. A ripe female attaches a clutch of reddish eggs to the cave ceiling and from that point tends them essentially alone. Apistogramma clutches are small — congeners typically lay on the order of 40–150 eggs, and uaupesi falls in that range (no published wild fecundity figure exists for the species, so this is a genus-typical estimate, flagged as such). Eggs hatch in roughly two days; the female then gathers the larvae into a pile on the cave floor and, after about another week, emerges leading a school of free-swimming fry, which she shepherds and defends aggressively. Reproduction is tightly gated by water chemistry: keepers who breed the fish describe maintaining roughly pH 5.5 for routine care but dropping to pH 4.0 or even lower to get viable, fertile eggs — extreme conditions that are difficult to hold stable and that few plants tolerate. As one experienced breeder put it bluntly, this is not a first dwarf cichlid to learn breeding on.
In the aquarium
Apistogramma uaupesi is rarely kept even among dwarf-cichlid specialists, and should be treated as an advanced species from the moment of purchase. It is a true blackwater extreme — not a fish that tolerates "soft-ish" tap water or a pH of 6.5 as some dwarf cichlids will. The natural range sits at pH 4.0–5.0 with near-zero carbonate hardness, and hobbyists report that a male kept at pH 6 remains alive but refuses to color up, court or spawn. A dedicated tank is strongly advised. A single pair or a harem group (one male with two or three females) can be kept comfortably in a 23.5–31.5 in (roughly 15–20 US gal) footprint; a longer tank — 35.5 in or more — is better for a harem, as it gives females room to hold distinct territories away from one another and from the male. Height matters less than floor space.
The biotope brief is unambiguous: fine sand or fine-grain substrate, a deep layer of dried leaf litter (Indian almond, oak, beech), multiple small cave structures (halved coconut shells, clay pots, or purpose-built ceramic caves), and dense planting or tangles of driftwood to break sightlines. Lighting should be dim — floating plants and surface cover help. Filtration must be gentle; these fish live in near-still, tannin-black, microbe-rich water, not in flow. A sponge filter or low-turnover canister with a spray bar aimed at the glass is appropriate. Water chemistry is the non-negotiable piece: pH 5.0–5.5 for routine maintenance, achievable reliably through RO or rain water with Indian almond leaf extract and a small amount of peat or alder cones. Hardness should be negligible — under 2 °dGH, ideally under 1 °dGH. Temperature can sit in the 75–81 °F range for general husbandry. Do not attempt to keep this species in dechlorinated tap water unless your tap water is genuinely very soft and acidic; most municipal supplies are far too hard and too alkaline even after conditioning.
Tankmates are a complicated question. In the wild, Apistogramma uaupesi lives alongside small tetras, pencilfish and similar characins — and a school of small, unobtrusive dither fish (hatchetfish, slender pencilfish such as Nannostomus marginatus, small Moenkhausia species suited to blackwater) can reduce the male's territorial fixation and make the females feel secure enough to come out. However, any fish large enough to eat an adult uaupesi, or aggressive enough to harass the female on her cave, is unsuitable. No other bottom-dwelling cichlids or similarly-sized territorial fish belong in the same tank. Keep in mind that this species stays small — under 1 in standard length for males — and a 2 in characin is not as small a companion as it might appear.
Sexing is straightforward once fish are near adult size: males are larger, carry a taller, sail-like dorsal and a lyrate caudal with a central red-to-copper wedge; females are smaller and rounder-finned, and breeding females flush vivid yellow from chin to belly. Getting a compatible pair is less straightforward. Breeders on specialist forums note that Apistogramma uaupesi pairs can be genuinely picky — two fish housed together will sometimes simply ignore each other indefinitely, and forcing the situation by removing all escape routes tends to end in fin damage rather than spawning. Running a small group from the outset, letting the male's preference emerge, produces better results than a forced pairing.
Common keeper mistakes, in rough order of frequency: (1) water that is not soft or acidic enough — this is the single most common cause of failure; (2) a tank too small or too bare to let females establish separate territories, leading to female-on-female aggression; (3) introducing the species into an established community tank with tetras that nip or outcompete it; (4) expecting breeding behavior at pH above 5.5 — experienced breeders push pH to 4.0–4.5 and near-zero hardness to reliably trigger spawning, conditions that also require very frequent small water changes with prepared water since buffering capacity is essentially absent; (5) overlooking that the male's display behavior — the flickering dorsal, the lateral band flashing on and off — is the primary sign of stress or arousal, and a fish that never raises its dorsal is telling you something is wrong. This is not a beginner's dwarf cichlid, but for a keeper who can hold genuine blackwater conditions it is genuinely rewarding — the red-wedge display and the speed of the male's fin movements are as striking as anything in the genus.
Conservation
Apistogramma uaupesi is assessed as Least Concern on the IUCN Red List (assessment by R. G. Frederico, dated 4 November 2020, carried in the 2025-2 update; e.T85282016A85282020), with an unknown population trend. The reasoning is that, although the species is significantly traded for the aquarium hobby, it occupies a very large and still largely pristine range, so the trade is not judged to threaten it at the species level. Tellingly, Brazil's own national assessment (ICMBio's 2018 Livro Vermelho) lists the fish as Data Deficient and describes it as rare and locally low in abundance — a more cautious read than the global Least Concern. (The Cichlid Room Companion's species page, last revised in 2008, still shows the species as "not evaluated"; that record simply predates the 2020 assessment.)
The one concrete pressure on the species is collection for the ornamental trade: wild fish are valuable, which sustains continued wild harvest, though the IUCN states the impact on wild populations is simply not known and calls for monitoring of catch methods and volumes. In the wider basin context, the Rio Negro is a comparatively well-preserved blackwater system — far less developed than the white-water Amazon mainstem — but the broader Amazon faces mounting strain from deforestation, sedimentation, hydropower and a warming climate, as documented across the Neotropical fish literature. For a leaf-litter blackwater specialist, the relevant long-term risks are degradation of the forested, tannin-rich headwaters its chemistry depends on, and poorly regulated collection — not population collapse. Stated plainly: the species itself is currently Least Concern even as the basin around it is increasingly pressured, and the prudent course is to favor captive-bred fish where available and to support sustainable, locally beneficial wild fisheries.