Taxonomy & naming
The Brazilian ichthyologist Henrique R. Varella and the American ichthyologist Mark H. Sabaj Pérez described the species in 2014, in a paper whose title — "A titan among dwarfs" — sums the fish up in three words (Ichthyological Exploration of Freshwaters 25(3):243–258). Aquarists and field workers had known it for several years before that under the informal label Apistogramma sp. "gigas", or "giant Apistogramma", after its discovery on a 2009 expedition to the Serra do Cachimbo funded by the All Catfish Species Inventory. The holotype is an adult, brooding male of 3 in standard length, held at the Museu de Zoologia da Universidade de São Paulo as MZUSP 115057; the type locality is an unnamed tributary of the rio Curuá (rio Iriri drainage, rio Xingu basin) at the BR-163 bridge in Pará, Brazil (8°49'12"S, 54°58'11"W), collected on 22 January 2009. The epithet honours the Swedish ichthyologist Sven Oscar Kullander (b. 1952), whose four decades of work effectively built the modern taxonomy of Neotropical cichlids, and of Apistogramma in particular — a fitting tribute for the most spectacular member of a genus he did so much to organise. Apistogramma is among the largest of all cichlid genera, with well over a hundred described and undescribed species. Varella and Sabaj Pérez placed Apistogramma kullanderi tentatively in the Apistogramma regani lineage, while admitting that its conspicuously large body sits more comfortably with the Apistogramma steindachneri lineage — so its exact branch within the genus is left genuinely open in the original description.
Morphology
Size is the headline. The largest measured male reached 3 in standard length and the largest female 2.5 in; FishBase rounds these to roughly 3 in SL for males and 2.5 in SL for females. In a genus whose wild-caught adults usually stop near 2.5 in SL, that makes Apistogramma kullanderi a heavyweight — and a visibly deeper, more robust one, with a body depth of 34–41% of standard length rather than the slim build most hobbyists picture. Mature males carry a coarse, irregular scatter of dark spots and vermiculations over the cheek and gill cover, and 10–12 dark stripes along the flanks, each running the seam between adjacent scale rows and set off by a paler centre to every scale; the ground colour in life is gold to yellow-orange, and the caudal fin is broad and evenly rounded. Males also develop distinctly enlarged jaws with thick, fleshy lips, five dentary pores where look-alikes have four, and an angular head with a concave dip between the eyes — the features the describers use to tell them from close relatives such as Apistogramma rubrolineata and Apistogramma tucurui. The females are the more distinctive sex: in brooding dress they show an unusual continuous band of intense dark pigment along the base of the dorsal fin and across the underside from throat to anal-fin base, broken by dark vertical bars — a pattern approached among relatives only by Apistogramma baenschi, in which the dorsal pigment is discontinuous. Fin counts run 13–16 dorsal spines with 6–8 soft rays, 3 anal spines with 7–8 soft rays, and 23–24 vertebrae; immature fish wear a dark midlateral band rather than the rounded midlateral blotch typical of the genus.
Habitat
Apistogramma kullanderi is a narrow-range endemic of the upper rio Curuá and two of its larger tributaries, on the Serra do Cachimbo plateau in Pará, Brazil. The Curuá feeds the rio Iriri, which feeds the rio Xingu, one of the great clearwater rivers of the southeastern Amazon. What sets this stretch apart is that the fish lives above a sequence of large waterfalls — the describers map falls on the order of 40 and 197 ft high, plus a 33 ft drop at a small hydropower weir — which cut the upland reach off from the rest of the Xingu and leave a fish fauna strikingly poor in cichlids. The tributaries run clear to mild blackwater, and the specimens came from shallow, sluggish backwaters shaded by overhanging bank vegetation: a low-energy world of leaves and roots rather than open current. The original description gives the habitat in those qualitative terms but publishes no in-situ pH, conductivity, temperature or depth, so the figures in this article's fact box are not field measurements for this species — they are drawn from the soft, warm, acidic clearwater and blackwater chemistry typical of upper-Xingu headwater streams and from the conditions in which the fish breeds in captivity. Read that way, the water is best understood as soft and acidic (roughly pH 5–7), warm (about 75–84 °F), and shallow (on the order of 0–3 ft in the backwaters sampled). The handful of cichlids it shares water with include Aequidens aff. rondoni, pike cichlids (Crenicichla) and the rheophilic Teleocichla, along with a second, smaller, still-undescribed Apistogramma of the upper Curuá that is never found together with it.
Feeding
No one has studied what Apistogramma kullanderi eats in the wild — it is a recently described fish from a remote watershed, and the type series was preserved rather than opened up for gut contents — so most of what can be said comes from its anatomy and from the genus. FishBase puts it at a trophic level near 3.5, in line with a micro-predator that takes small aquatic invertebrates, insect larvae and other benthic prey gleaned from leaf litter, sand and submerged wood, as dwarf cichlids do generally. Its enlarged jaws and thick, fleshy lips suggest a sturdier feeding apparatus than a typical dwarf, and may reflect the larger, harder prey a bigger fish can handle — but no specialised diet has actually been recorded, so treat that as a lead rather than a finding. In its impoverished headwater community it is one of the larger small-bodied cichlids, working the quiet, shaded margins while pike cichlids and Teleocichla take the faster, more structured water. In the aquarium it takes live and frozen foods readily, which fits a generalist invertebrate-eater rather than a fussy specialist.
Mating
Like other Apistogramma, Apistogramma kullanderi organises its breeding around a defended female territory rather than a shoal. Keepers who have spawned it describe pairs that are calm and tolerant outside breeding, then a sharp change of gear once the female ripens: she takes on an intense black breeding dress, claims a cave or sheltered surface, and turns markedly aggressive, often driving the male well away. That female-dominant, post-spawning aggression is the single most consistent behavioural note across independent keeper accounts from the UK, Sweden and elsewhere, and it dictates how the fish is managed. The describers point out that the genus's strong size dimorphism is most pronounced in polygynous species, where males defend spawning territories and larger males breed more successfully — and they fold this into their case that an isolated, competitor-poor watershed gave sexual selection the room to push Apistogramma kullanderi toward its outsized body. In practice, both pair-only and harem set-ups have produced spawns: one Swedish breeder keeps each female in her own tank of about 25 US gal and rotates a single male between them, while other keepers find that only single, well-matched pairs will settle and breed.
Breeding
Apistogramma kullanderi is a substrate-spawning cave brooder rather than a mouthbrooder. The female lays her eggs on a sheltered surface — a cave roof, an upturned flowerpot, a cleft in the wood — then guards and tends the eggs and fry, while the male, if she tolerates him, defends the wider territory. (The holotype itself was a brooding male, a reminder that males stay engaged at the spawning site.) No wild clutch has been documented; captive broods are modest, with several keepers reporting roughly 30 fry and occasionally up to 70 or so from a large, well-conditioned female, and a fair expectation that the count climbs as the fish reach full size — though those numbers come from the aquarium, not a wild egg count. The most reliable husbandry detail comes from the small circle who have bred it, and their accounts converge tightly: spawning happens in very soft, acidic water — typically pure reverse-osmosis water around 50–60 ppm total dissolved solids and about 81 °F (81 °F) — triggered by heavy feeding of live foods. Because the female becomes aggressive once she is on eggs, some breeders pull the male after the eggs hatch; others leave him a week or two and report he never touches the fry. The fry are notably large for a dwarf cichlid and grow slowly but stay robust, which makes them comparatively easy to raise once a spawn is secured. The species' reputation, then, is not that it is hard to breed — several keepers call it easier than many smaller Apistogramma — but that it is rare, costly and slow to mature.
In the aquarium
Apistogramma kullanderi is genuinely rare in the hobby — collected in tiny numbers from a remote Pará watershed, and expensive when captive-bred stock appears (£300–350, ≈ €350–410, per pair in UK breeder threads). Buying a single-watershed endemic before the hobby has a self-sustaining captive population carries some responsibility, so returning fry to the trade should be a goal.
Tank: a male reaching 3 in SL, and robust for his length, is not a fish for the 60-litre nanos that suit Apistogramma cacatuoides or Apistogramma borellii. Allow at least 25 US gal (roughly a 90 × 40 × 17.5 in footprint) for a pair, and 40 US gal or more for a harem. It is also more assertive than most congeners, so a longer tank with broken sightlines beats a square one. Use sand or fine gravel and recreate the shaded, low-energy margins of the upper Curuá with a deep bed of dried leaves (Catappa and Guava), coconut-shell caves, Mopani root tangles and potted plants; dim lighting keeps the colour from washing out.
Water: target pH 5.5–6.8 and well under 100 ppm TDS (reverse-osmosis water blended to 50–80 ppm is the breeders' standard), at 79–84 °F (79–84 °F). It will live at pH 7.0 or a little above but will not breed reliably there. Weekly 30–40% water changes hold the chemistry steady, and because the fish has little tolerance for dissolved nitrogenous waste, a well-cycled, lightly stocked tank and a gentle, quality filter are non-negotiable.
Tankmates: small, peaceful and chemistry-compatible. A school of 10–12 soft-water characins — cardinal or rummy-nose tetras and the like — makes good dither, and soft-water Corydoras are acceptable bottom companions. Avoid anything that competes for caves, bullies a brooding female or wants harder water, including other cave-spawning cichlids; the larger Crenicichla that share its native range are unsuitable in any domestic tank, and two males together will almost certainly end badly.
Sexing and pairs: males are clearly larger (to ~3 in versus ~2.5 in), with heavier, fleshy-lipped jaws and full striated flanks, while non-breeding females are smaller, plainer and rounder-bellied. Keep a committed pair or a small harem (one male, two or three females, each with her own cave); for a first attempt, a single well-matched pair is least fraught. The fry take newly hatched brine shrimp and microworms from the start. The usual mistakes are a tank too small, water too hard and too alkaline, too little cover, and pairing fish before either has reached full size — this species does not reward shortcuts.
Conservation
Apistogramma kullanderi has not been assessed by the IUCN Red List — Not Evaluated, as of FishBase's 2025 reading of the list — and it carries no CITES listing. That blank is typical of Amazonian cichlids, most of which are either Least Concern or simply unevaluated and are tracked through the taxonomic literature rather than by conservation status. As an ornamental fish, its main direct pressure is targeted collection for the aquarium trade, but its remoteness has kept that pressure low: it has never been a high-volume trade species, and one field assessment in AMAZONAS Magazine judged that the number of wild fish taken for the hobby is no threat to the population at present — partly because demand for dwarf cichlids has cooled and the fish is now bred in captivity. The more meaningful risk is about place, not over-collection. This is a single-watershed endemic, confined above waterfalls on the upper Curuá; its entire world is a small upland system in the Xingu headwaters — exactly the kind of restricted range where local habitat change counts for a great deal — and the type locality already sits beside a small hydropower weir. The wider Xingu basin is under real strain from large-scale hydroelectric development (Belo Monte on the lower river is the best-known example, but small hydro reaches into the headwaters too), deforestation and gold mining, all of which alter flow, sediment and water chemistry; the basin's exceptional endemism has made these impacts a recurring concern in the regional conservation literature. The honest summary: the species itself is not formally threatened and faces little collecting pressure, but a narrow-range, single-stream endemic in a damming, land-use-pressured basin has very little margin — and it deserves the proper IUCN assessment it still lacks.