Taxonomy & naming
Charles Tate Regan described this fish in 1908 as Heterogramma steindachneri, from material taken at Georgetown on the lower Demerara River, Guyana. The two syntypes are held at the Natural History Museum, London (BMNH 1909.4.30:31-32), and the species was redescribed from Surinamese material by Kullander & Nijssen in their 1989 monograph The Cichlids of Surinam, which fixed the type catalogue and the modern concept of the species. The epithet honours the Austrian ichthyologist Franz Steindachner (1834-1919), who had earlier reported Guianan cichlids of this lineage under other names. Heterogramma was later folded into Apistogramma, a genus name from the Greek apisto ("uncertain") and gramma ("line"), alluding to the variably developed, often incomplete lateral line that runs through the group.
Like many early-imported dwarf cichlids, Apistogramma steindachneri accumulated junior synonyms before its identity settled: Apistogramma ornatipinnis (Ahl, 1936) and Apistogramma wickleri (Meinken, 1960) both fall into synonymy, the latter a name that lingered in the hobby for a large blue domestic strain. A further wrinkle is hobby misidentification rather than nomenclature — for decades almost every fish sold in North America as Apistogramma ortmanni (a regani-group species) was in fact Apistogramma steindachneri, and in the 1970s imported Apistogramma macmasteri also passed under the steindachneri name. Today Apistogramma steindachneri is the type species of the steindachneri species-group (DATZ aquarium codes A130-A139; the Demerara form is A138), which molecular work nests within the broader Apistogramma pertensis lineage. Kullander's chapter in the 2003 Check List of the Freshwater Fishes of South and Central America (CLOFFSCA) is its standard distributional reference, and Eschmeyer's Catalog of Fishes confirms the valid name.
Morphology
This is a comparatively large, deep-bodied Apistogramma rather than a flashy one. Adult coloration is largely silvery to bluish on the flanks, with a golden-yellow shoulder, blue-tinted ventral fins, and red trim along the tips of the dorsal and caudal fins; many males carry rows of red spots striping the tail. The diagnostic mark is a black lateral spot that sits squarely on the lateral line — the patch is a shared feature of the whole species-group, but its placement directly over the lateral line distinguishes true steindachneri — paired with a narrow lateral band and a round spot at the caudal-fin base. The intensity of that black patch is mood-dependent and can fade out entirely.
Reported maximum size varies, and the disagreement is worth stating plainly. Taxonomic sources are conservative: the Catalog of Fishes and FishBase cite a largest recorded male of 2.5 in standard length, with females to roughly 3 in total length. Seriously Fish lists males to 3 in. Experienced keepers consistently report bigger animals — males to about 4 in (4 in), and the old wickleri strain reportedly larger still. The gap likely reflects well-fed aquarium fish outgrowing wild-measured specimens. Sexual dimorphism is strong: males are markedly larger and heavier, developing a characteristic squared-off to lyrate (lyre-shaped) caudal fin with extended top and bottom rays at about half adult size, while females are smaller and rounder-tailed, often showing a black abdominal stripe and black ventral fins and turning vivid canary-yellow in breeding condition.
Habitat
Apistogramma steindachneri is a fish of the Guiana Shield's coastal rivers rather than the Amazon proper. The Catalog of Fishes gives its range as the Essequibo, Demerara, Mahaica and Suriname (to Corantijn/Marowijne) drainages of Guyana and Suriname, with a closely similar form in eastern Venezuela whose conspecificity is still unresolved; the IUCN assessment extends the mapped range westward to the upper Rio Branco basin in Roraima, Brazil. That western edge is the species' only real Amazon connection — the Rupununi savanna, where the headwaters of the Essequibo and the Branco meet and seasonally exchange water, sits at the margin of its distribution. Specialists caution that fish sold on Manaus export lists as "steindachneri" from the Branco are often near-relatives such as Apistogramma hippolyte or Apistogramma cf. rupununi rather than true Apistogramma steindachneri.
In the wild it favours slow, shaded tributaries, forest creeks, ponds, pools and lake margins, typically over sand with leaf litter, submerged wood and overhanging vegetation; collectors note it is not especially abundant where it occurs, and a good catch can take real effort. Water type spans black, clear and white water, and the measured chemistry is striking in its range — pH from roughly 3.9 to 7.3, with temperatures from the mid-70s into the high 80s Fahrenheit (about 24-31 degC, most collection sites in the 80s) — but with one constant: the water is consistently very soft, generally under 1 dGH. FishBase's narrower captive-keeping envelope (pH 6.2-6.8, dH 3-10, 20-25 degC) reflects aquarium practice rather than the full field range. Most records are shallow, from marginal pools and creeks no more than a metre or two deep.
Feeding
Like the genus as a whole, Apistogramma steindachneri is a benthic micro-carnivore. It forages along the bottom over sand and leaf litter, taking small invertebrates — insect larvae, micro-crustaceans and other meiofauna sifted from the substrate and the decomposing litter layer. FishBase places it at a trophic level of about 3.4, squarely in the small-predator range. The leaf-litter biotope it occupies is itself a productive microhabitat: as drowned leaves and wood break down they support the biofilm and tiny invertebrates that both adults and, especially, fry depend on. In the aquarium this translates to a fish that readily accepts live and frozen Artemia, Daphnia and bloodworm and learns to take quality prepared foods. Its place in the community is that of a small, secretive bottom-dweller sharing space with other shield-water fishes such as Nannacara, Krobia, Crenicichla species, killifish and small characins.
Mating
Apistogramma steindachneri is polygynous: in the wild, and in roomy tanks, a single male holds a territory overlapping the smaller territories of several females, a classic dwarf-cichlid harem. The mating system runs on the genus's division of labour. A ripe female — flushed bright yellow — selects a cavity and lures the male toward it; he waits at the entrance and enters only briefly to fertilize, since a large male often cannot fit inside the chamber his much smaller mate has chosen. Pair formation is brief and the female drives it. Males are seriously territorial toward one another: two males in one tank without heavy structure or a crowd of rivals to disperse the aggression usually ends with the dominant fish relentlessly hunting the weaker, a point keepers raise repeatedly. Toward females and at spawning the male is far less of a problem than in many showier Apistos, which is part of why this species earns its forgiving reputation.
Breeding
Apistogramma steindachneri is a cave-spawner with maternal care that is among the easier Apistos to breed. The female lays her eggs on the ceiling of a cave — FishBase records 60-120 eggs in wild-derived observation, with the male defending the surrounding nesting sites — then takes sole charge of guarding and fanning the brood, becoming the dominant aggressor and keeping the male patrolling the territory perimeter. Eggs hatch in roughly 36-72 hours depending on temperature, with fry free-swimming a few days later. In smaller single-pair tanks the male will sometimes join in active biparental care, an exception to the usual female-only pattern that several keepers, including the breeder behind DwarfCichlid.com, have observed directly; in larger harem set-ups the male rarely participates.
The experiential record from keepers is consistent and vivid, and where FishBase's wild count is modest, aquarium spawns are routinely much larger: multiple long-time breeders independently report 150-250 fry per spawn, prolific enough that finding homes for the offspring becomes the real problem. One widely cited account records roughly 400 fish from two consecutive spawns that came out essentially all male even though the two batches were reared in different tanks at different temperatures — a pointed reminder that temperature-influenced sex ratios in dwarf cichlids are unpredictable. Breeding is undemanding by Apistogramma standards: a peaceful pair will spawn in a tank as small as ten gallons, though a male with a harem wants a footprint near 36-40 in (35.5–39.5 in) and several caves (flowerpots and coconut shells work fine) arranged so territory-holding fish cannot see each other. Like all Apistos it is intolerant of accumulated nitrogenous waste, so a mature filter and regular partial water changes are non-negotiable, and rare wild imports should be quarantined for internal parasites.
In the aquarium
Apistogramma steindachneri has a reputation it has largely earned: it is one of the most forgiving Apistogramma a newcomer to the genus can choose. Unlike the finicky blackwater specialists that make up much of the dwarf-cichlid hobby, this species tolerates a genuinely wide range of water chemistry. pH anywhere from the high 5s through neutral, and hardness up to about 10 dGH, is accepted without evident stress, making it possible to keep in tap water that would slowly undo many of its Peruvian or Colombian relatives. Temperature should sit in the upper range — 26-30 degC (79-86 degF) suits it well, reflecting its warm Guianan origins — and should not be run cool as some keepers do with more temperate dwarf cichlids. That said, the one chemistry demand the whole genus shares applies here too: accumulated nitrate and ammonia will kill it just as surely as they kill any sensitive cichlid, so a cycled filter and consistent partial water changes of around 25-30% weekly are non-negotiable.
Because Apistogramma steindachneri is among the largest Apistogramma, a single pair warrants at least a 60-litre (15-US-gallon) tank with a 23.5 in footprint; a male managing a harem of two or three females genuinely needs a 35.5–47 in tank to work properly. The substrate should be fine sand — this species, like all Apistos, sifts the bottom and should not be kept over coarse gravel that will abrade its gills and mouth. A thick covering of dried Indian almond or oak leaves is strongly recommended: the leaf litter replicates the decomposing-litter microhabitat it uses in the wild, provides shelter, supports the microfauna that fry will graze, and buffers pH modestly in softer setups. Multiple caves are essential — clay flowerpots laid on their sides, halved coconut shells, and purpose-made ceramic caves all work; site them so that the entrances face different directions so females holding separate territories cannot see into each other's caves. Driftwood and robust plants (Anubias and Microsorum anchored to wood perform best on sand) complete the decor.
Tankmates should be chosen with some care but the species is not nearly as demanding about company as many smaller Apistos. Small, peaceful characins — rummy-nose tetras, ember tetras, cardinal tetras — make ideal dither fish: their activity in the upper water column draws a nervous female out into the open and breaks up line-of-sight aggression between territorial fish. Corydoras catfish are safe bottom companions and help clean up missed food. The fish to avoid are other cichlids that compete for the same cave sites (any Apistogramma of similar size, or Nannacara that holds territory at the same level) and obviously any fish large enough to regard a female steindachneri as prey. Within the species itself the main risk is male-on-male aggression: two males in the same tank without a divider and substantial territory between them will fight to the point of injury, so a single-male harem is the standard arrangement.
Sexing is straightforward once fish are sub-adult: males grow noticeably larger and develop the characteristic squared-off to lyrate caudal fin with extended outer rays. Females are smaller, stay more uniformly coloured, and — the clearest field sign — flash a vivid canary-yellow with a crisp black ventral stripe and dark abdominal patch when guarding eggs or fry. Even juvenile fish can usually be sexed by relative size once they reach about 1 in; males grow faster from the start. In breeding condition a female's yellow colour change is dramatic enough that experienced keepers can see it from across the room.
For a keeper used to Amazonian blackwater Apistos, the main mistake with Apistogramma steindachneri is over-softening and over-acidifying the water out of habit. This is not a fish that needs pH 5 and near-zero hardness; pushing the chemistry that far while providing poor water-change discipline can actually do more harm than keeping it in neutral, moderately hard tap water with excellent maintenance. The other common error is understocking on caves. A female guarding eggs will drive the male relentlessly unless he can retreat to structure she cannot pursue him into; without enough broken sightlines the harassment can turn lethal. With adequate space, good cave density, a fine-sand substrate, leaf litter, and attentive water maintenance, Apistogramma steindachneri is a genuinely rewarding species — hardy, interesting in behaviour, and willing to breed in the hands of a keeper who has just started exploring the genus.
Conservation
The IUCN Red List assesses Apistogramma steindachneri as Least Concern (assessed 29 October 2020 by R.G. Frederico; current Red List version 2025-2), on the strength of its wide range — an estimated extent of occurrence spanning Guyana, Suriname, eastern Venezuela and Brazilian Roraima. The population trend is listed as unknown, with no documented threats and the candid note that the species does not appear to be especially common or abundant. Its only recorded human use is as an ornamental fish; it is taken for the aquarium trade but is of no food-fishery interest and carries no CITES listing. Collection pressure is light and, given how rarely it now enters the trade, currently negligible — its scarcity in shops since the late 1990s reflects market economics (newer species are more profitable to import and farm), not population decline.
Placing it in its wider setting requires honesty about which water it belongs to. Most of its range lies in the Guiana Shield's coastal rivers, not the Amazon; the neotropical cichlid literature that frames it — Kullander's CLOFFSCA cichlid chapter (in Reis, Kullander & Ferraris 2003) and the older synthesis of South American fish ecology by Lowe-McConnell — treats this as a region of soft, often acidic black- and clearwater streams. The species touches the Amazon basin only at its western margin, in the upper Rio Branco and the Rupununi savanna where Branco and Essequibo waters seasonally intermingle. Those headwater and shield habitats are, for now, comparatively intact, but they are not immune: regional pressures from gold-mining (and its mercury and sediment loads), deforestation and shifting land use are the realistic long-term concerns for shield and upper-Branco fishes, far more than collection. The fair summary is the one IUCN itself implies — the species is secure by virtue of range, we simply know very little about its populations, and the threats that matter are habitat-level and diffuse rather than any collapse aimed at this fish.