Taxonomy & naming
Laetacara flamannellus was described in 2012 by Felipe P. Ottoni, Pedro H. N. Bragança, Pedro F. Amorim and Cecile S. Gama, in the journal Vertebrate Zoology (volume 62, number 2, pages 181–188), under its present name — there is no synonymy to untangle, as the species has never been placed in another genus. The holotype, an adult of 1.5 in standard length catalogued as UFRJ 8060, was collected on 10 January 2011 by Bragança and Amorim from lago Curiaú, reached along the AP-70 road toward Santo Antônio da Pedreira in the Macapá municipality of Amapá state, Brazil (0°00′54″N, 51°02′26″W); numerous paratypes are held at the UFRJ, MNRJ and IEPA collections. The genus Laetacara, erected by Sven Kullander in 1986 for the small 'smiling' or dwarf acaras, sits in the tribe Cichlasomatini of the subfamily Cichlinae, and is regarded as closely allied to the dwarf genera Nannacara and Cleithracara; Kullander diagnosed it in part by a deep notch in the dorsal margin of the anterior ceratohyal bone, a feature shared among cichlids only with Cleithracara, which the describers confirmed in the new species. Within the genus, Laetacara flamannellus is most similar in counts, body form and overall preserved colour pattern to the flag acara Laetacara curviceps and to Laetacara dorsigera, the three forming a group set apart from their congeners by a dark spot on the dorsal-fin base. Its description brought the genus to seven valid species at the time, making Laetacara the ninth-most-speciose genus of the subfamily Cichlinae.
Morphology
This is a very small cichlid: the type series ran 1–1.5 in in standard length, FishBase lists a maximum of about 1.5 in SL, and even allowing for tail length a large adult is only around four centimetres. The body is short, deep and laterally compressed — body depth is roughly 40 percent of standard length — with a steep forehead, the rounded-snout 'smiling' profile that gives the genus its name, and small caniniform teeth in three rows on each jaw. Living fish are spectacular for their size. The flanks are light brown crossed by seven dark, often forked vertical bars, overlaid with blue and green iridescence and an interrupted dark longitudinal stripe; the diagnostic feature, and the source of the name, is a dark brown-to-black spot at the base of the dorsal fin ringed by an intense orange 'flame.' The fins carry the boldest colour: the dorsal fin has a blue ground crossed by a continuous bright-yellow stripe running from the first spine to the tip, the anal and pelvic fins are intense yellow shot with blue, and the caudal fin is blue with yellow bars and metallic dots edged in bright purple. The describers separate it from its two closest relatives by the orange ring around the dorsal spot (absent in Laetacara curviceps and Laetacara dorsigera), from Laetacara dorsigera by lacking the conspicuous red belly that breeding fish of that species develop, and from Laetacara curviceps by the unbroken yellow dorsal stripe plus several scale characters. No marked external difference between the sexes was reported in the description; in keeping with the genus, ripe females are expected to be rounder-bodied, but the distinction in this species is not documented.
Habitat
Laetacara flamannellus is a narrow-range endemic of the eastern coastal river floodplains of Amapá state in northern Brazil — a set of small drainages isolated from the main Amazon basin, north of the river's mouth — recorded between Igarapé do Davi in Amapá municipality and córrego Areal in Mazagão municipality, with the type locality at lago Curiaú near Macapá. The Catalog of Fishes extends the range to the border area with French Guiana. The eastern plains of Amapá are a mosaic of dry and seasonally flooded land; the flooded portion, roughly a tenth of the state, carries flooded forest and flooded grassland that appear only in the January-to-June rainy season, when the rivers overflow and form the temporary lakes known regionally as ressacas. Most specimens, including the holotype, came from exactly this setting: still (lentic) water close to the bank, about 5 ft out from the margin, in very shallow places only 12–19.5 in deep, among stands of sedge-like Cyperaceae. One contrasting collection was made in a flowing creek (igarapé) in shallow water about 15.5 in deep on the flooded margin. The annual mean air temperature of the region is about 82 °F, and the fish shares these waters with other small species — the killifish Rivulus schuncki, juvenile Hoplerythrinus unitaeniatus and a Nannostomus pencilfish in the grasslands, and a richer cichlid community in the creek including Apistogramma gossei, Crenicichla inpa, Satanoperca jurupari, and unidentified Krobia and Mesonauta. Specific water-chemistry readings were not published with the description, but these are warm Amazonian coastal lowland waters, and the genus as a whole occupies soft, slightly acidic conditions.
Feeding
No gut-content study has been published for Laetacara flamannellus, but its anatomy and its relatives place it clearly as a micro-predator of small invertebrates. The Cichlid Room Companion characterises the species as insectivorous, and FishBase estimates a trophic level near 3.1 — the level of a small carnivore rather than a detritivore or herbivore. Like other smiling acaras it would forage over the bottom and through marginal vegetation, taking insect larvae (including the chironomid midge larvae that abound in shallow weedy water), small crustaceans and other tiny invertebrates, and picking at the substrate. In the dense Cyperaceae beds of its ressaca habitat — described by the authors as an ideal site for small fish to feed and breed because of the rapid bloom of plankton and plant growth when the floods arrive — such food is seasonally abundant, and the dwarf acara occupies the role of a small, unobtrusive invertebrate-picker low in the shallow-water food web.
Mating
Courtship and pair behaviour have not been described in the wild or in captivity for this particular species, so what can be said is drawn from the well-studied biology of its close relatives, above all the flag acara Laetacara curviceps and Laetacara dorsigera. Laetacara are monogamous, forming a stable bond between a single male and female that together hold and defend a small territory; the Cichlid Room Companion explicitly records this species as monogamous. Pairing is typically preceded by mutual display — the fish flare fins, present their flanks and the bright dorsal markings, and clean a chosen spawning surface together — and the partners then share territorial defence against intruders. By the modest standards of cichlids these are peaceable, retiring fish; aggression is largely confined to the immediate area around the nest and to the breeding season. In a species whose entire world is the shallow weedy edge of a temporary lake, that low-key, pair-based territoriality fits a habitat where cover is dense and rivals are close at hand.
Breeding
Reproduction in Laetacara flamannellus has not been documented; it is presumed, on the strength of its genus, to be a biparental substrate spawner. In Laetacara generally the pair selects and meticulously cleans a flat surface — a broad leaf, a flat stone, or a patch of firm substrate — and the female lays a single layer of adhesive eggs there, which both parents then guard and fan. In well-studied congeners the eggs hatch in roughly two days at tropical temperatures, after which the parents move the wrigglers to one or more shallow pits dug in the substrate, shepherd the free-swimming fry as a tight school, and continue to guard them for some time; clutch sizes in the genus are typically on the order of a hundred or so eggs (with much larger spawns of several hundred reported for well-conditioned flag acaras). The flooded grasslands the species inhabits are, in the describers' words, an ideal nursery — the rainy-season flood brings warmth, cover and a bloom of plankton just as small fish would need to raise young — so spawning is most plausibly timed to the January-to-June inundation. None of the fine detail (egg number, incubation period, fry development) has been confirmed for Laetacara flamannellus itself, and the figures above should be read as genus-typical rather than measured for this fish.
In the aquarium
Laetacara flamannellus is, for practical purposes, not an aquarium fish. Seriously Fish notes that it is unclear whether the species has ever genuinely entered the hobby, and that any specimens in circulation were most likely traded as the far commoner flag acara, Laetacara curviceps, which it closely resembles. There is no established body of keeping or breeding experience specific to it, and it is not offered through ordinary commercial channels. Anything written about its care is therefore an inference from its biology and from the husbandry of its close relatives, and should be treated as such.
If the fish were kept, its requirements would follow from where it lives: warm, soft, slightly acidic water and the calm, heavily planted shallows of a flooded grassland. A modest tank would suffice for so small a cichlid — a pair would be comfortable in something on the order of 23.5 in / 20 US gal — furnished with fine sand, leaf litter, driftwood and dense planting along the margins to mimic the sedge beds it hides among, plus flat stones or broad leaves as potential spawning sites. Gentle filtration and gentle flow suit a fish of still marginal water; bright open expanses do not. Temperature in the high twenties Celsius (matching the ~82 °F regional mean), a pH on the acidic side of neutral, and soft water would reflect its native conditions, and small live and frozen foods — bloodworm, daphnia, brine shrimp, microworm — would match its invertebrate-picking diet. As a tiny, mild, retiring cichlid it would be vulnerable to boisterous or much larger tankmates and best kept in a quiet community of small Amazonian fishes, or in a species tank for any attempt at breeding. The honest summary, though, is that this is a rarely seen, poorly documented fish that the average aquarist will never encounter, and most 'Laetacara flamannellus' in the trade are likely to be something else.
Conservation
The IUCN Red List assesses Laetacara flamannellus as Data Deficient (DD), assessed on 7 November 2018 by the Brazilian federal conservation agency ICMBio (Instituto Chico Mendes de Conservação da Biodiversidade) and published in the 2022 edition. The assessment records a population trend of unknown and states plainly that it is not possible to evaluate whether the species faces threats given current knowledge — there is simply too little information on its distribution, abundance and ecology to place it in a threat category. It carries no CITES listing. That said, a Data Deficient rating should not be read as reassurance: this is a small-bodied, narrow-range endemic confined to the coastal floodplains of a single Brazilian state, an environment of seasonal ressacas whose existence depends on intact rain-fed flood regimes and whose grasslands are exposed to the cattle ranching, drainage, fire and land-use change that affect Amapá's flooded plains. A range that small, tied to a fragile seasonal habitat, is inherently more vulnerable than its current Data Deficient listing can capture, and better field data are the precondition for any meaningful assessment.