Taxonomy & naming
Apistogramma hoignei was described in 1965 by the German aquarium ichthyologist Hermann Meinken (Senckenbergiana Biologica 46(4): 257–263), from fish collected the year before in Venezuela. The type locality is the Río Portuguesa — a tributary of the Río Apuré near Santa Rosa, in the Venezuelan Llanos. The name honours Emil 'Leo' Hoigne (died 1996), an Argentine-born aquarist and collector settled in Valencia, Venezuela, who caught the original specimens and shipped them to Meinken in Germany.
The founding story has a twist. Meinken thought he was working from a male and a female, but when the Swedish ichthyologist Sven O. Kullander re-examined the types for his 1979 revision of the Orinoco Apistogramma (Zoologica Scripta 8: 69–79, with the hoignei redescription on p. 75), he found both fish to be females — an easy mistake, since females across this lineage are notoriously hard to tell apart. Kullander upheld the species regardless, and it has stood ever since; FishBase, GBIF and Eschmeyer's Catalog of Fishes all list it as Apistogramma hoignei Meinken, 1965, with no junior synonyms.
The genus belongs to the Neotropical eartheater subfamily Geophaginae. Apistogramma is one of the most species-rich South American cichlid genera — roughly seventy-plus valid species and many more undescribed — and Apistogramma hoignei sits in the macmasteri complex of the macmasteri species group, within the wider regani lineage. In the hobby's DATZ 'A-number' system it is coded A116, with two related Orinoco forms (an 'Arauca' fish and a second variant) taking the neighbouring codes A117 and A118. Its closest look-alikes are Apistogramma macmasteri, Apistogramma viejita and Apistogramma hongsloi, and the steady stream of newly described Orinoco congeners shows how much of this lineage remains unresolved.
Morphology
By the standards of the genus this is a stocky fish. FishBase lists a maximum of 2.5 in standard length and Seriously Fish gives 2–2.5 in SL, while experienced keepers report the largest males reaching about 3.5 in — roughly 3–3.5 in — once the trailing fins are counted. Females stay noticeably smaller.
Males are the show sex, in the usual dwarf-cichlid pattern: larger, more colourful, and carrying more extended finnage. The best field mark is the caudal fin, which tends to be slightly lyrate with distinct coloured margins along its top and bottom edges — solid red, solid black, or in some populations both together. Some fish add a tall, serrated dorsal with long anterior lappets; others show only modest fin extensions. Warm yellow often washes the face and forebody, and many individuals wear dark facial markings and the 'black head' look noted in the comparative literature — though keepers and identifiers warn those head marks are variable and not a dependable diagnostic. A brooding female turns yellow with the dark blotches typical of the genus. Because the species ranges widely and overlaps with several look-alikes — Apistogramma macmasteri, Apistogramma viejita, Apistogramma hongsloi — colour and finnage shift from one collection point to the next; meristics such as the higher anal-fin spine counts noted by Staeck separate it from some relatives, but in practice a confident identification usually comes down to provenance rather than any single feature.
Habitat
Despite the odd 'Amazon' listing, Apistogramma hoignei is an Orinoco-basin fish of Venezuela and Colombia — and the most broadly distributed Apistogramma in that basin. FishBase summarises its range as the Portuguesa, Arauca and lower Caura drainages plus the lower Orinoco mainstream down to Barrancas. The IUCN assessment breaks this into three areas: the lower Orinoco and Gulf of Paria region of eastern Venezuela; the western Llanos around the Apure and Arauca; and a southern outlier in a lagoon of the lower Río Guaviare in Colombia.
Everywhere, it favours slow water — tributaries, backwaters, creeks and lagoons, and the lowland palm-swamp formations Venezuelans call morichales and esteros: slow, often clear water draining from Moriche-palm wetlands, floored with fallen leaf litter and edged with dense marginal plants. It is a shallow, leaf-litter fish. FishBase carries no measured depth band, so the figures here are a habitat-typical estimate — roughly the top 3 ft of these shallow creeks and lagoon margins — rather than a published range. Its in-situ chemistry is remarkably catholic: the IUCN account, drawing on Mesa & Lasso's Orinoco Apistogramma review, records everything from productive, near-neutral water (about pH 6.9–7.7, 120–200 µS/cm) to acidic, oligotrophic blackwater (about pH 3.6–4.6, 10–60 µS/cm). Field collectors on Apistogramma.com report sites as soft and acidic as pH 5.4 at 20 ppm TDS — a reminder that conductivity stays low across the range even where pH climbs toward neutral. Recorded temperatures run about 73–84 °F (73–84 °F).
Feeding
Apistogramma hoignei is a small benthic micro-predator. The IUCN account calls it plancto-entomophagous — a taker of planktonic prey and insect larvae — and FishBase estimates a trophic level near 3.4. Seriously Fish describes it feeding mostly on benthic invertebrates in the wild, the standard niche of the genus: a fish that works the leaf litter and soft bottom for small crustaceans, insect larvae and other invertebrates rather than grazing algae or filter-feeding.
In its communities it is a small mid-level player. Across the morichal and Llanos habitats it shares water with tetras, the dwarf cichlid Mikrogeophagus ramirezi, Corydoras and other small catfishes, and the juveniles of larger fishes that move onto the flooded plains in the dry season — along with the medium-sized predators that keep dwarf cichlids cryptic and tied to cover. Its 'medium' resilience and low fishing-vulnerability scores on FishBase fit a small, fast-maturing, widely distributed species.
Mating
Like most of its genus, Apistogramma hoignei builds cave-centred territories that can settle into a polygynous, harem structure: one large male holds a stretch of bottom and courts several females, each guarding her own small cavity inside his range. The heavy build comes with real attitude. Field and hobby accounts agree that males need room to establish, and that females need many small hiding places the bulkier male cannot follow them into. Males also spar elaborately with one another — flaring fins, lateral displays, mouth-wrestling — often at length and without serious injury, the ritualised contest behaviour familiar across Apistogramma. Pairing runs through the female: a ripe female colours up, leads the male to her chosen cave, and the territory tightens around it as spawning nears.
Breeding
Apistogramma hoignei is a cave-spawning substrate breeder with maternal care. The eggs are stuck to the ceiling of a cavity — a crevice, an undercut, a hollow among roots or leaf litter, or a flowerpot in captivity — and the female alone tends them and guards the fry while the male patrols the wider territory. The IUCN account reports very early maturity (around two months), clutches of roughly 50–70 eggs, and an absolute fecundity near 450 over a season, all consistent with a small, opportunistic, fast-cycling fish.
The most consistent behavioural signal from keepers is post-spawning female aggression. Across independent reports on Apistogramma.com and other forums, breeders describe females turning hyper-aggressive in fry care and driving off — sometimes killing — the male, with several losing males during breeding attempts. Treat that as well-corroborated anecdote; it fits the maternal-care biology of the macmasteri group. On the plus side, the species has a reputation as one of the easier macmasteri-group apistos to spawn, breeding across a fairly wide range of soft, warm conditions. Soft, acidic water, dim light, leaf litter and a snug cave are the usual triggers, and the female herds the free-swimming fry through the litter once they leave the cave.
In the aquarium
Apistogramma hoignei reaches the hobby only sporadically — more often through specialist breeders than a local shop — but once settled it is not especially demanding, and experienced apisto keepers rate it among the more manageable macmasteri-group species. It is still a fish for someone already comfortable with dwarf cichlids, not a first cichlid.
Tank: because it is larger and pushier than a slender apisto like Apistogramma borellii or Apistogramma cacatuoides, footprint matters. A 90-litre tank (about 24 gallons, 90 × 15.5 in) is a workable minimum for a single pair; for a harem of one male and two or three females, or any community, 30 US gal with a long footprint is a more honest starting point. The male can be genuinely territorial and will harass perceived rivals, so floor space and sight-breaks matter more than raw volume. Fine sand is essential — the fish sifts and noses the bottom in the manner of the genus — and a heavy scatter of dried leaf litter (Indian almond, oak, beech) against the back and sides recreates the morichal floor, tints the water gently, and builds the micro-territories the females need. Half-buried terracotta pots on their sides, coco-husk halves, stacked flat stones or commercial ceramic caves all serve; each female needs at least one cave the male cannot enter, so a 1 in opening that a 5-cm female can slip through but a 7-cm male cannot is ideal. Floating plants and emergent cover (pothos roots, Ceratopteris) lower the light and give females somewhere to break line-of-sight.
Water: chemistry is one of this species' more forgiving traits. The wild range spans pH 3.6 to 7.7 and takes in both productive, near-neutral Llanos water and acidic palm-swamp blackwater (see Habitat), so fish from Llanos stock genuinely tolerate harder, moderately alkaline tap water. In practice, pH 6.0–7.2 and soft-to-moderate hardness (up to roughly 10–12 °dH) cover most tap-water situations, and many breeders work at pH 6.5–7.0 without trouble. For conditioning and spawning, softening below 5 °dH and easing pH toward 6.0–6.5 tends to trigger behaviour. Hold temperature at 75–81 °F for maintenance and nudge it to 81–82 °F for breeding. Stable parameters and regular small water changes matter more than chasing extreme softness, and — as across the genus — nitrate should stay below 20 mg/l.
Tankmates: dither fish earn their place. A group of rummy-nose or cardinal tetras, or a school of Corydoras sterbai (whose temperature range overlaps well), works the open water, signals safety and draws the fish out of hiding, which in turn eases friction between male and females.
Common mistakes: the usual error is underestimating the male's aggression toward females outside spawning — without genuine bolt-holes, a female can be harassed to death. The related mistake is leaving the male in once a female has spawned; brooding females routinely turn on and kill him (see Breeding), so keep a divider or spare tank ready for when eggs appear. For sexing, males are larger and more colourful, with the lyrate coloured-edged caudal and longer dorsal lappets, while females are smaller and plainer and flush vivid yellow with dark lateral blotches when brooding. Stock a harem as one confirmed male with at least two females; a lone pair concentrates all his attention on a single target.
Conservation
Apistogramma hoignei is listed as Least Concern on the IUCN Red List (assessed by Lina Mesa-Salazar on 21 July 2020). The reasoning is simple: it is the widest-ranging Apistogramma in the Orinoco basin, with an estimated extent of occurrence around 240,0 mi², and although no population figures exist, much of that range lies outside active hydrocarbon or mining zones. Its use in the ornamental trade is listed as unknown, it is not covered by CITES, and collection pressure on the species looks minor — partly because it reaches the market only now and then.
That clean status sits inside a basin under real strain, and the assessment is careful to name the threats where the range does meet industry. In Bolívar State, its distribution overlaps gold, diamond, iron and bauxite mining in the Cuchivero, Caroní and Upata systems; across the eastern and western Llanos the heaviest pressure is the Orinoco Oil Belt, the vast heavy-crude province along the south side of the lower Orinoco, whose extraction, effluent and spills can salinise and warm the water and cut its clarity and productivity. Part of the range does fall inside protected areas, including Venezuela's Aguaro-Guariquito National Park and Colombia's Estrella Fluvial de Inírida RAMSAR wetland.
The wider Neotropical picture points the same way. In the standard regional inventory (Kullander, 2003, in the Check List of the Freshwater Fishes of South and Central America), most Orinoco and Amazon cichlids are catalogued without elevated threat status, and the limnological tradition behind Lowe-McConnell's work frames these whitewater, blackwater and clearwater fishes as resilient to natural flood-pulse extremes but exposed to habitat change — sedimentation, pollution, hydrological alteration — rather than outright collapse. For Apistogramma hoignei the plain summary holds: the species itself is Least Concern and not a present conservation worry, even as parts of the Orinoco it lives in face real and growing extractive pressure.