Taxonomy & naming
Cichla pleiozona was described by Sven O. Kullander and Efrem J. G. Ferreira in their 2006 review of the genus Cichla (Ichthyological Exploration of Freshwaters 17(4): 289-398), the monograph that split the long-overburdened "Cichla ocellaris" and "Cichla monoculus" into a far larger set of species and erected nine new ones, this fish among them. It sits in the cichlid subfamily Cichlinae, tribe Cichlini — the exclusively South American peacock basses — and the genus name traces to the Greek kichle, a wrasse. The species epithet is the informative part: pleios ("more") plus zona ("girdle"), a nod to the additional vertical bar across the caudal peduncle and the usually distinct occipital bar that set it apart from look-alikes.
The holotype is held at the Museu de Zoologia da Universidade de São Paulo (MZUSP 92398), with a paratype series split between the Swedish Museum of Natural History in Stockholm (NRM, several lots collected by G. Loubens in the Bolivian lowlands) and the Instituto Nacional de Pesquisas da Amazônia (INPA) in Manaus. The type material spans the Bolivian Mamoré and Beni systems and the Brazilian side of the upper Madeira. Catalog of Fishes, FishBase and GBIF all treat the name as valid and uncontested; the IUCN notes "no relevant taxonomic limitations." Vernacular names follow regional language: tucunaré in Portuguese, pavón in Spanish, and "Bolivian peacock bass" in the English-language trade.
Morphology
This is a mid-sized peacock bass. The largest verified specimens run to about 17 in (17.5 in) standard length and roughly 5.3 lb (2.4 kg) (FishBase), modest by the standards of giants like Cichla temensis but still a substantial, deep-bodied predator. The body is the fusiform, slightly compressed peacock-bass shape — a big terminal mouth, a projecting lower jaw, and the notched, two-part dorsal fin typical of the genus — and adults typically wear the eponymous ocellated "eyespot" on the caudal fin base, a black blotch ringed in pale gold that gives the group its name.
The diagnostic features Kullander and Ferreira used are worth knowing, because Cichla pleiozona is easily confused with its close relatives Cichla kelberi and Cichla monoculus. It shows three dark vertical bars on the flank plus a fourth bar (bar 4) set forward on the caudal peduncle — the "extra girdle" of the name — which is usually absent in those two species, and large individuals develop a pronounced dark occipital bar across the nape. It lacks the black or ocellated markings on the side of the head seen in some congeners, carries irregular dark blotches along the front of the belly, and has a higher lateral scale count (84-93, versus 76-83 in kelberi and 68-87 in monoculus). It differs further from kelberi in lacking the pale spots that species scatters on its anal and pelvic fins and the lower lobe of the caudal. As in most Cichla, breeding males develop a fleshy nuchal hump on the forehead, and spawning fish flush their barred pattern into stronger contrast — the clearest sexual difference in an otherwise weakly dimorphic genus.
Habitat
Cichla pleiozona is a fish of the upper Madeira — the great clearwater-to-whitewater drainage that gathers the southwestern Amazon. Its native range covers the Rio Madre de Dios, Beni, Mamoré and Guaporé river systems of Bolivia and the adjacent Brazilian states of Mato Grosso, Rondônia and Amazonas, plus the Rio Jamari, a tributary entering the Madeira itself (Kullander & Ferreira 2006; FishBase; IUCN). The historic stretch of rapids on the middle Madeira near Porto Velho long acted as a biogeographic filter, and Cichla pleiozona is essentially the peacock bass of the basin above it. The IUCN puts its extent of occurrence at roughly 1.1 million km².
In the wild it occupies the warm, lowland floodplain world of the region — main river channels, oxbow and floodplain lakes (lagunas), and slower backwaters across the Llanos de Moxos wetlands of the Bolivian Amazon, where survey collections routinely turn it up. Like the rest of the genus it favors warm water; hobby and aquarium-trade accounts of Cichla converge on a roughly 78-86 F (26-30 C) range, and the fish is intolerant of cool temperatures. Precise in-situ chemistry for this species is thin in the literature, which is honest to admit — FishBase records no depth, temperature, pH or hardness figures for it, and the genus review and regional fish surveys document where it lives more than the water it lives in — but the upper Madeira tributaries it favors are typically soft and slightly acidic, the floodplain norm for the basin (pH roughly 5.5-7.5).
Feeding
Peacock basses are the apex daytime piscivores of their reaches, and Cichla pleiozona is no exception. FishBase places it at a trophic level of about 4.3 — firmly carnivorous, near the top of the food web — and it hunts as a diurnal, visually oriented ambush-and-pursuit predator, the ecological role its big mouth and torpedo build are shaped for. Adults take fish as the overwhelming bulk of the diet, with juveniles relying more on insects and smaller prey before shifting onto a fish-dominated menu as they grow, the ontogenetic diet shift documented across the genus. Across the Amazon it is a recognized predator on small fishes — AMAZONAS Magazine (Nov/Dec 2021) lists peacock bass (Cichla spp.) among the natural enemies that armored catfishes such as Corydoras evolved their locking spines against.
In the upper Madeira this makes it both a meaningful predator on smaller fishes and a commercial food fish in its own right. Studies of the Madeira basin note that commercial fishing for Cichla pleiozona, alongside the detritivore Prochilodus nigricans, concentrates in the low-water season when fish are crowded into shrinking channels (de Lacerda et al. 2024). Its high trophic position has a less appetizing side effect: as a long-lived top predator it bioaccumulates methylmercury, and the Madeira — a basin with a long history of gold-mining contamination — has made Cichla pleiozona a recurring subject of mercury-monitoring studies, where it consistently shows elevated tissue concentrations relative to lower-trophic species.
Mating
Direct reproductive data for Cichla pleiozona specifically are sparse, so what follows leans on the well-documented and consistent biology of the genus, flagged as such. Cichla are monogamous and form pairs that hold and defend a territory through the spawning cycle — this is pair-bonded, biparental care, not the harem mouthbrooding of the African rift-lake cichlids the genus is often mentally filed alongside. As courtship builds, males develop the breeding nuchal hump noted above and both partners flush their barred pattern into stronger contrast.
Outside of breeding, peacock basses are not schoolers in the tight sense but tend to move and hunt in loose groups; pairs split off and become aggressively territorial as they come into spawning condition. Aquarium breeders of the genus report that warm, stable conditions, conditioning on live and meaty foods, and enough space to let a pair form and choose a site are the usual triggers — and that a courting pair will brook no tankmates within its patch. These are community-corroborated patterns from hobbyist breeding accounts rather than published work on this particular species, and are presented in that spirit.
Breeding
Once a pair has bonded, Cichla spawn as biparental substrate spawners: the pair cleans a flat hard surface — rock, sunken wood, or a swept patch of firm substrate — and lays a sheet of adhesive eggs, after which both parents guard the clutch. When the young hatch and become free-swimming, the parents herd the fry in a tight school, often shifting them between excavated pits in the sand and shepherding the cloud of young through the shallows. Both sexes defend eggs and fry vigorously against anything that approaches.
Clutches in the genus are large — many hundreds to low thousands of eggs in the bigger species — and the extended guarding of free-swimming fry schools is the defining reproductive signature of Cichla, distinguishing it sharply from the mouthbrooders. Species-specific clutch and timing data for Cichla pleiozona are not published; the pattern above is the consistent, well-attested genus biology and is offered as such rather than as a measured account of this particular fish.
In the aquarium
Cichla pleiozona reaches the aquarium trade now and then as a "Bolivian peacock bass," and the honest hobbyist verdict is the same one that applies to every Cichla: this is a big-tank specialist's fish, not a community cichlid. Even at the genus's smaller end, a foot-and-a-half of fast, predatory cichlid needs serious room — keepers across MonsterFishKeepers, Cichlid-Forum and AquariumAdvice converge on tanks measured in hundreds of gallons with a long footprint (think six feet and up), not because the fish is tall but because it is a powerful, stiff-bodied cruiser that needs swimming length. The widely repeated "180 gallons for an adult" figure is a realistic floor, not a comfortable target, and the smaller grow-out tanks people start them in are exactly that — temporary.
Water should be warm (roughly 78-84 F / 26-29 C), soft to moderate, and on the slightly acidic side, with the heavy, well-maintained filtration a messy piscivore on a meaty diet demands; these fish foul water quickly. Feed prepared carnivore pellets and meaty frozen foods rather than a long-term diet of live feeder fish, which carry disease and do nothing the fish needs nutritionally. Tankmates are a real problem: anything small enough to swallow will be eaten, and anything large enough not to be still has to tolerate a territorial predator, so robust similarly-sized companions in a very large tank are the only honest option. The mistake new keepers make, again and again, is buying a charming 3-inch juvenile without a plan for the 15-inch adult — and peacock basses grow fast.
Conservation
Cichla pleiozona is assessed by the IUCN Red List as Least Concern (assessment e.T49829675A159171807), assessed by Renata Guimarães Frederico on 5 November 2020 and published in the 2023 freshwater-fish update. The justification is straightforward: despite little species-specific data, it has a very wide range across the upper Madeira and appears to be common, with an unknown but not obviously declining population. No species-specific threats are recorded, and it is not listed on CITES. Its main documented use is as a regional food fish — taken nationally for human consumption in Bolivia and Brazil — and there is no evidence that this harvest currently threatens the species. In short: this is a secure fish, not a strained one, and it should be described that way.
That security sits within a basin that is anything but unstressed. The Amazon's southwestern arm has been reshaped by the large Madeira hydroelectric dams (Santo Antônio and Jirau near Porto Velho), by deforestation and shifting land use across Rondônia and the Bolivian lowlands, and above all by a long legacy of artisanal gold mining that has loaded the Madeira with mercury — which, as a top predator, Cichla pleiozona concentrates in its flesh (de Lacerda et al. 2024). There is also a cautionary genus-level footnote: peacock basses are among the most damaging fish South America has exported to its own reservoirs and to the wider tropics, where introduced Cichla have driven down native small-fish abundance (Franco et al. 2022). Cichla pleiozona itself is flagged as an introduction within Bolivia in at least one invasive-species registry. The honest summary, consistent with the wider Amazon literature (e.g. Kullander 2003 in the Check List of the Freshwater Fishes of South and Central America), is that this is a Least Concern species in a working, contaminated and dam-altered basin: not at risk of collapse, but a useful sentinel for the health of the water it lives in.