Taxonomy & naming
The Swedish ichthyologist Sven O. Kullander described Apistogramma caetei in 1980, as part of his taxonomical study of the genus published through the Zoological Museum of the University of Amsterdam — the same work in which he named roughly a dozen new Apistogramma at once and began imposing order on a sprawling, confusing genus. The species has stood exactly as first combined ever since; FishBase, Eschmeyer's Catalog of Fishes, and the Catalogue of Life all list it as valid with no junior synonyms. Its types come from the Atlantic coastal drainage of northeastern Pará: the type locality is an unnamed igarapé (a small forest stream or canal) near Bragança, in the Rio Caeté system, and the species is recorded from the Apeú and Caeté rivers around that town.
Apistogramma caetei gives its name to the caetei-complex, which Mike Wise — the long-time moderator of apistogramma.com and author of the widely used species-group framework — places in the Apistogramma regani-Group of the larger Apistogramma regani-Lineage. Wise describes the complex as medium-sized, relatively robust dwarf cichlids whose males carry diagonal abdominal streaks beneath a narrow zig-zag lateral band, vertical rows of spots across the whole caudal fin, and a lateral band that ends at the seventh body bar with a distinctive downward, right-angled 'break' just ahead of the caudal spot. He counts only one securely described member — Apistogramma caetei itself — plus perhaps three other described species of uncertain placement and at least six undescribed forms, so the complex is best read as a still-unsettled grouping built around this one anchor. The name is also notoriously over-applied in the trade: Wise has repeatedly flagged that wild imports sold as Apistogramma caetei frequently turn out to be resticulosa-complex fish such as Apistogramma sp. 'Wangenflecken' — a caution worth carrying into any account of the species.
Morphology
Even among Apistogramma this is a small fish. FishBase gives a maximum of about 1.5 in standard length for males and around 1.5 in for females, and Wise keeps caetei-complex fish under roughly 3 in total length — so a mature adult is really a fish of three to five centimetres. The build is the usual dwarf-cichlid one, laterally compressed and moderately deep, but notably more robust than the slender members of neighbouring groups.
The colour pattern is the complex's signature and the surest way to name a fish in hand. A narrow, zig-zagging dark lateral band runs back along the male's flank to the seventh vertical bar, where part of that bar darkens just below the band to make the characteristic downward right-angle 'kink' immediately ahead of a discrete caudal spot. Thin diagonal streaks cross the lower abdomen, and the whole caudal fin is patterned with vertical rows of small spots. The species is sexually dimorphic in the genus's usual way: males grow larger and carry the bold tail-spotting and extended finnage, while females stay smaller and plainer, then turn an intense yellow when breeding or tending a brood. Because so many lookalikes are traded under this name, experienced keepers confirm a true Apistogramma caetei by this exact combination — band-break, abdominal streaking and caudal spotting — rather than by colour alone.
Habitat
Apistogramma caetei lives in the small Atlantic-coastal drainages of northeastern Pará around Bragança — the Apeú and Caeté systems, the latter giving the fish its name. This is east of the main Amazon mouth, in a belt of humid coastal forest streams rather than the great whitewater or blackwater rivers of the interior. The wider caetei-complex, as Wise maps it, runs along these Atlantic streams from the Rio Parnaíba north to the Ilha de Marajó at the Amazon's mouth and into Amapá near Macapá, with relatives in the Rio Tocantins system; Apistogramma caetei itself sits in the Bragança part of that arc.
No one has published a field study of its specific biotope, so the finer habitat detail has to be read from the genus and from aquarium experience. FishBase classes it as a benthopelagic freshwater fish of tropical streams, with a pH of about 6.5–7.0, hardness from roughly 10 dH upward, and temperatures of about 73–86 °F. That tolerance of near-neutral, moderately hard water sets it apart: unlike the blackwater-dependent Apistogramma of the Rio Negro or western Amazon, Apistogramma caetei is one of the genus's more adaptable members, which is exactly why it became an easy aquarium fish. Like its relatives it is a bottom-oriented dweller of structured shallows — leaf litter, submerged wood, roots and crevices in slow forest streams, where cover doubles as feeding ground and spawning site — though for this species that picture is inferred rather than documented in situ. FishBase carries no depth figure; consistent with a small dwarf cichlid of shallow igarapés, its working depth is best taken as the top metre or so of water (roughly 0–3 ft).
Feeding
No one has published a diet study of Apistogramma caetei, and FishBase carries no stomach-content data for it; the trophic level it lists (about 3.3) is a model estimate from body size and close relatives, not a field measurement. What can be said rests on the well-established biology of the genus. Apistogramma are micro-predators of the streambed — small benthic invertivores that pick insect larvae, microcrustaceans, worms and other tiny invertebrates from the substrate, leaf litter and biofilm, often taking a mouthful of fine sediment and sorting the edible items from it. In the aquarium Apistogramma caetei behaves the same way, thriving on small live and frozen foods — the live foods that hobby sources single out for conditioning Apistogramma — and taking prepared foods readily, in keeping with its undemanding reputation. In its home streams it would fill the same low-level invertivore niche, working the bottom and litter layer while itself serving as prey for larger fishes; the specifics, though, stay undocumented, and are given here as genus-level inference rather than observed fact for this species.
Mating
Apistogramma caetei follows the genus's reproductive playbook: a cave-spawning dwarf in which the female takes over brood care, forming harems where conditions allow. FishBase records it plainly as 'a harem spawner when the opportunity arises' — a single dominant male holds a territory that overlaps the smaller territories of several females, each of whom spawns and raises young largely on her own in her own cave. This female-tending, harem-polygynous system, rather than the strict biparental monogamy of many larger Neotropical cichlids, is the norm across most of Apistogramma, and it is why the standard way to keep the species is one male with several females in a well-planted, cave-rich tank.
Courtship in the genus revolves around the cave and around the female's dramatic switch to a vivid yellow, high-contrast dress, with which she signals readiness and later herds her brood. Males patrol and defend the wider territory, displaying with spread fins and lateral posturing, while females compete among themselves for the best spawning sites. The ethology specific to Apistogramma caetei — its exact courtship sequences, triggers, and wild harem dynamics — has never been formally described, so this account reflects the consistent, well-documented pattern of the genus and of aquarium spawnings rather than a dedicated study of this fish.
Breeding
Breeding is the best-attested part of this fish's biology, because it spawns readily in captivity and the basic mode is on record in FishBase. Apistogramma caetei is a substrate cave-spawner: the female lays her eggs on the ceiling of a cave — a rock crevice, a hollow under wood, or in aquaria an inverted half-flowerpot — the male fertilizes them, and the female alone then tends the clutch. FishBase puts that clutch at up to about 200 eggs glued to the ceiling, with the female fanning and guarding first the eggs and then the wrigglers inside the cave while the male patrols the larger territory.
Once they hatch, the yolk-bearing larvae stay in or near the cave until they absorb their yolk and become free-swimming fry, at which point the female leads and herds the school through the territory, flashing her yellow brood livery to signal danger and keep them massed. Being a hardier, less chemistry-sensitive Apistogramma, Apistogramma caetei is one of the more straightforward dwarf cichlids to spawn — soft, slightly acidic water and live foods improve results, as they do across the genus, but it does not need the extreme blackwater its relatives demand. Precise figures for incubation time, wild brood size and fry growth have not been published for this species, so the developmental timeline here is drawn from general Apistogramma experience rather than from a study of Apistogramma caetei.
In the aquarium
Apistogramma caetei is one of the more forgiving members of the genus, and for anyone who can source genuine specimens it makes a rewarding, if not widely kept, project. The one real caveat is up front, not in the tank: because the name is so routinely misapplied in the trade, verifying identity is the first job of keeping the species.
Tank: A 15–20 US gal aquarium suits a single male with two or three females. This fish stays under 3 in total length at most, and most adults are three to five centimetres, so footprint and broken sightlines matter more than raw volume — males are territorial, and females need visual breaks to avoid being harassed to exhaustion. A 60-cm long tank is a workable minimum; 31.5 in or more lets the harem structure function properly.
Water: This is where Apistogramma caetei diverges pleasantly from the fussier dwarfs. FishBase places its tolerance at pH 6.5–7.0 with a hardness floor around 10 dH and no recorded upper ceiling, matching its origin in coastal Pará rather than the near-distilled blackwaters of the Rio Negro. Keepers with moderately hard tap water who would struggle with Apistogramma nijsseni or the more sensitive regani-group species can often keep this fish without elaborate treatment, as long as pH stays around or below 7.0 and the water is not actively hard. Temperatures of 75–82 °F cover the comfort range, and a reliable heater matters more than the exact setting. Soft, slightly acidic water and live or frozen foods still improve breeding, as they do across the genus, but they are not required for healthy maintenance.
Decor: Mimic the structured shallow stream — fine sand or fine gravel, a scatter of dried leaf litter, bog-wood or twisted roots, and, critically, multiple caves. Spawning caves can be commercial ceramic ones, inverted half-flowerpots with a notch cut in the rim, smooth stones stacked into an overhang, or lengths of PVC pipe laid on their side. One cave per female is the minimum, and more is better: competition for preferred sites is the engine that drives a working harem. Fine-leaved and floating plants soften the light — Java fern, Anubias, and frogbit or Salvinia all tolerate the warmth. Like most Apistogramma the species is sensitive to dissolved waste, so regular partial water changes and gentle filtration (a sponge filter or a reduced-flow hang-on) matter more than an elaborate setup.
Tankmates: The safest partners are small, peaceful upper-water schoolers that stay out of the bottom zone and act as dither fish — small tetras such as cardinal, ember or small rummy-nose, plus pencilfish or hatchetfish. Dither fish visibly reduce a dwarf cichlid's skittishness and draw out more natural behaviour. Moderate-sized Corydoras are generally fine, though very small ones may be chased near spawning sites. Avoid other bottom-dwelling cichlids (including a second Apistogramma unless the tank is very large), aggressive or fast midwater fish, and anything big enough to eat an adult; shrimp colonies do not survive a breeding pair, since the adults eat shrimp and the female clears any near her fry.
Common mistakes: Sexing is easy at adult size — males are larger, with the full caetei-complex pattern and extended finnage, while females are smaller and plainer, turning vivid yellow when gravid or guarding young. The usual errors are failing to confirm identity (given the chronic mislabelling of resticulosa-complex fish under this name, buy from a specialist retailer or breeder), keeping too few females or too few caves so male aggression falls on one fish, and neglecting water quality, which in a small, densely planted tank can crash pH before obvious signs appear. If purchased fish do not match the marks in Morphology above, treat them as an undetermined caetei- or resticulosa-complex fish rather than Apistogramma caetei proper — the care is much the same, but the identification matters to anyone keeping records or reporting a spawn.
Conservation
The IUCN Red List assesses Apistogramma caetei as Least Concern, in an assessment dated 7 November 2018 by the Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio), Brazil's federal conservation agency, carried under Red List version 2025-2. The species has no CITES or CMS listing, and FishBase rates its fishing vulnerability as low (10 of 100) and its resilience as high, with a minimum population doubling time of under 15 months — the expected profile of a small, fast-maturing, fecund dwarf cichlid.
Least Concern here reflects the absence of any documented range-wide threat rather than close population monitoring, and that absence is itself the caveat. Apistogramma caetei occupies a fairly restricted set of Atlantic coastal drainages around Bragança in Pará, a part of eastern Amazonia under steady pressure from deforestation, agriculture and expanding settlement — and small-range stream fishes in such landscapes are exactly the ones whose status can shift faster than assessments catch. The fish is collected for the ornamental trade, but because it is hardy and easily bred, much of what reaches aquarists is or could be captive-produced, limiting wild-harvest pressure. No species-specific concern is on record; the honest summary is that Apistogramma caetei is judged secure for now, while its wild populations remain poorly studied and its coastal-Pará habitat is not immune to the broader degradation of eastern Amazonian streams.