Taxonomy & naming
Lina María Mesa-Salazar and Carlos A. Lasso described Apistogramma intermedia in 2011, in their monograph 'Revisión del género Apistogramma Regan 1913 (Perciformes, Cichlidae) en la cuenca del río Orinoco,' published by the Instituto Alexander von Humboldt in the Serie Editorial Recursos Hidrobiológicos y Pesqueros Continentales de Colombia. It was one of eight new Apistogramma the revision teased out of the lower-Orinoco fauna. Eschmeyer's Catalog of Fishes lists it as valid — Apistogramma intermedia Mesa S. & Lasso 2011, original account on p. 121, Fig. 54 — a standing upheld by Schindler & Staeck (2013) and by Lasso & Machado-Allison (2024); FishBase likewise treats it as valid.
The holotype is MHNLS 829, held at the Museo de Historia Natural La Salle in Caracas, with paratypes MHNLS 8208, 12482 and 19862. The type locality, per the Catalog of Fishes, is the Río Caura, caño El Cambur — a creek crossed by the road bridge about 3 mi from the Río Caura — in Estado Bolívar, Venezuela. 'Intermedia' is Latin for 'intermediate' or 'in the middle'; the authors and the ETYFish Project read it as a nod to the fish's median or average size ('la talla media'). Within the lower-Orinoco fauna the species is most easily confused with Apistogramma hoignei, but differs in its unusually small size and other fine characters, and the two are geographically separate: Apistogramma intermedia is restricted to the Río Caura drainage and the lower Orinoco delta, where Apistogramma hoignei is absent.
Morphology
Apistogramma intermedia is among the smallest members of an already diminutive genus. The type series gives a maximum standard length of about 1 in SL (Mesa & Lasso 2011, as cited in Schindler & Staeck's comparative diagnosis of Apistogramma helkeri), with the holotype at roughly 1 in SL — near the very bottom of the size range for Orinoco Apistogramma, which span about 1–2.5 in SL across the genus. No live photographs of confirmed wild fish are widely available, and FishBase carries no maximum-length figure of its own. Like its congeners, the species was diagnosed on a combination of fine characters — squamation, pore counts, fin-ray and vertebral counts, lateral-spot and bar patterns, the shape of the caudal-fin markings, and body proportions — rather than any single striking feature, which is exactly why it had gone unrecognised within the lower-Orinoco fauna until the 2011 revision pulled it out of the 'Apistogramma hoignei' complex. Sexual dimorphism has not been documented for this species specifically. Apistogramma as a genus is strongly dimorphic, with larger, more colourful, longer-finned males and smaller, plainer females — but reading that onto Apistogramma intermedia would be inference, not observation.
Habitat
The species is endemic to the lower Orinoco system of Venezuela. The Catalog of Fishes gives its distribution as the Río Caura and the Orinoco River Delta, and the hobby-taxonomy compilations on tomc.no likewise place it in the lower Río Orinoco between the Río Caura and the delta. The type locality — caño El Cambur, a small Guiana-Shield blackwater creek reached from the bridge about 3 mi off the Río Caura in Estado Bolívar — sits in the lower Caura drainage at roughly 7.4°N, 65.2°W. Those coordinates are approximate, georeferenced from the named locality (El Cambur, Bajo Caura) rather than published in the description, so read them as indicative of the type creek, not exact.
As is typical for the genus, the fish is a shallow-water inhabitant of small forest creeks (caños) and channel margins, tied to leaf litter and submerged structure rather than open river. No in-situ temperature, pH, or depth measurements were published for Apistogramma intermedia itself, and FishBase lists no depth range. The water-chemistry tiles shown here are therefore basin-typical rather than site-measured: the Guiana-Shield blackwaters of the Caura and lower Orinoco are warm, soft and strongly acidic, generally around 77–84 °F and pH 4.5–6, the regime in which Orinoco Apistogramma normally live. Treat those figures as the expected envelope for the type habitat, not as readings taken from the type creek.
Feeding
No diet study has been published for Apistogramma intermedia. FishBase carries only a modelled trophic-level estimate of about 3.3, derived from body size and the trophs of close relatives rather than from gut contents. Judged by the well-documented habits of the genus, Apistogramma intermedia is expected to be a micropredator of small benthic invertebrates — picking and sifting tiny crustaceans, insect larvae and other meiofauna from the leaf litter and upper sediment of its creek habitat. For this particular species, though, that remains an inference from its congeners, not a recorded observation.
Mating
The mating system of Apistogramma intermedia has not been observed or described. Across the genus, Apistogramma are predominantly haremic to facultatively polygynous cave spawners: a dominant male holds a territory that overlaps the smaller territories of several females, each of which defends her own spawning cavity, and courtship turns on the female luring the male to her cave. Whether Apistogramma intermedia follows that script is unrecorded — the fish has not been kept and bred under a confirmed identification — so any account of its pair formation, courtship, or territoriality would be extrapolation.
Breeding
Breeding has not been documented for Apistogramma intermedia, in the wild or in aquaria. On the strength of its placement in the genus it is almost certainly a female-tending cave (substrate) spawner: the female lays a small clutch on the roof or wall of a concealed cavity and guards the eggs and larvae while the male defends the wider territory — inferred from Apistogramma generally, not confirmed for this species. No clutch count has ever been published for it; small-bodied congeners typically lay on the order of 40–80 eggs per spawn, so a clutch in that range is the reasonable genus-typical expectation, offered as inference rather than observation. Egg and fry development and spawning triggers are likewise unrecorded for this species.
In the aquarium
To the best of current knowledge, Apistogramma intermedia has never been kept in aquaria under a confirmed identification. It was described only in 2011 from a handful of preserved type specimens, has no circulating live photographs, and has not appeared in the European or North American Apistogramma trade under its own name. Any fish sold as 'Apistogramma intermedia' deserves scepticism until a comparison with the type-series morphology and a genetic barcode can support the identification. What follows is honest genus-typical guidance for a keeper who obtains a credibly identified fish; it leans on the well-documented care of small Orinoco Apistogramma in the pertensis/hoignei lineage rather than species-specific husbandry data, which does not yet exist.
Tank: Because Apistogramma intermedia reaches only about 1 in SL — one of the smallest Apistogramma known — a single male-and-harem group fits a modest tank. Roughly 15–20 US gal (a standard 23.5 in footprint) suits one male with one or two females; a 35.5–39.5 in tank is better if you add dither fish or intend a harem of three females. Floor area matters more than depth, since the fish lives in the shallow creek margins, rarely above 3 ft, with almost all its activity in the lowest 6 in of the water column. Use fine sand — ideally dark quartz or river sand — rather than gravel, which blocks the sifting the genus depends on, and scatter dried leaves (Catappa/Indian almond, guava, or similar) to build the tannin-rich leaf-litter microhabitat of the Caura's caños and help acidify the water.
Water: Chemistry is non-negotiable. The Río Caura and lower Orinoco are classic Guiana-Shield blackwaters — very soft (near-zero GH and KH), warm (77–84 °F) and strongly acidic (pH 4.5–6.0). A reverse-osmosis or deionised base topped up with blackwater extract or leaf tannins is the standard way to reach it. Tap water above about 100 µS/cm conductivity or pH above 6.5 will likely suppress spawning and can cause chronic stress over months; these are not preferences but the actual chemistry of the type habitat. Given the fish's tiny size and probable sensitivity, gradual acclimatisation and scrupulously stable conditions matter more than they would for hardier Apistogramma.
Caves & tankmates: Provide several spawning caves — coconut-shell halves with small openings, small clay pots on their side, or ceramic caves — set near or partly under leaf litter. As with all Apistogramma, the female picks a favoured cavity and defends it hard once claimed, so spare caves reduce female-on-female aggression in a harem; each should be just big enough for her to turn around inside, no larger, since these fish prefer snug sites. Small, non-competing dither fish that share the blackwater chemistry — small tetras (Hyphessobrycon or Moenkhausia), hatchetfish, or small Corydoras — help by signalling safety and drawing the cichlids out of hiding.
Common mistakes: The species' exceptionally small adult size makes tankmate choice a real concern; even moderately sized Apistogramma may out-compete or harass it, so until more is known it is safest kept as a species-only dwarf cichlid with only those small blackwater tetras and Corydoras. Sexing unseen fish is the usual puzzle — females of small Orinoco Apistogramma often develop a yellow-and-black facial pattern when guarding eggs, while males are larger and, in related species, longer-finned, though the extent of sexual dichromatism in Apistogramma intermedia itself is undescribed. Rate difficulty high, given the strict water chemistry, the rarity of correctly identified specimens, and the near-absence of keeper records. The classic error with any tiny blackwater Apistogramma is trying to keep it in general community conditions at neutral-to-alkaline pH: the Caura system's chemistry is the baseline, and straying far from it rarely ends well.
Conservation
The IUCN Red List assesses Apistogramma intermedia as Least Concern (assessor Lina Mesa-Salazar; assessed 23 July 2020), a category corroborated by FishBase's Red List feed. The species carries no CITES or CMS listing, and is rated of low fishing vulnerability and harmless to humans. Read that Least Concern listing with the usual caution for a narrowly known, recently described fish: it reflects the absence of identified range-wide threats across the lower Orinoco, not detailed population monitoring. The broader pressures on its habitat are those general to the lower Orinoco and Caura basins — deforestation, mining (including gold-mining sediment and mercury inputs in the Caura), and other land-use change that degrades the small forest creeks the genus depends on. Because so little is known about the species' true range and abundance, its conservation status is best treated as provisional.