Taxonomy & naming
Cichlasoma boliviense was described by the Swedish ichthyologist Sven O. Kullander in 1983, in his landmark monograph 'A revision of the South American cichlid genus Cichlasoma' (Swedish Museum of Natural History, Stockholm). That revision is the reason the name Cichlasoma — once a sprawling catch-all for scores of Central and South American cichlids — now applies only to a tight group of generalized, three- to six-anal-spined 'acaras' built around the type species Cichlasoma bimaculatum (Linnaeus, 1758). Kullander recognized boliviense as one of several geographically distinct, three-anal-spined forms that earlier workers had lumped under other names, and he diagnosed and named it as new. The holotype (IRSNB 677, in the Royal Belgian Institute of Natural Sciences) came from the Río Urugaita, a tributary of the Río Quizer in the Guaporé (Iténez) basin, about 8 mi south of San Xavier, Departamento Santa Cruz, Bolivia; a large paratype series is distributed across museums in Brussels, London, Chicago, Stockholm, Washington and Bonn. As the historian of the genus Willem Heijns has detailed, the fish had a long career under wrong names: earlier Bolivian records by Haseman (1911) and Fowler (1926) were reported as Aequidens portalegrensis (a species now restricted to far-southern Brazil), and specimens Karl-Heinz Lüling collected in 1969 from the Río Chaparé were split by Kullander (1976) between portalegrensis and bimaculatum — both populations are now understood to be boliviense. Within the family it sits in the subfamily Cichlasomatinae (Cichlinae of some classifications), the Neotropical 'acara' radiation. The epithet boliviense simply means 'of Bolivia,' for the country where the centre of its distribution lies.
Morphology
This is a small to medium acara-type cichlid. FishBase records a maximum of about 4 in standard length (around 4.3–4.4 inches, snout to tail base), so a fully grown adult, fins included, is a fish of roughly 4.5 in total — squarely in the size class of the better-known black acara and Port cichlid. The body is the typical Cichlasoma plan: oval, moderately deep and laterally compressed, with a gently sloping forehead and a terminal mouth suited to a generalized omnivore. Colour is unshowy by cichlid standards — a brassy tan to greyish-olive ground, paler below, often overlaid with a faint series of vertical bars and a scattering of dark flank markings, the whole capable of intensifying when a fish is in breeding dress or excited. Diagnostically, boliviense is one of the three-anal-spined members of the genus, a feature Kullander used (alongside scale counts and head proportions) to separate the various Cichlasoma forms; the count of three rather than four or more hard anal rays is part of what historically caused it to be confused with the southern Port cichlid. Sexual dimorphism is modest but real: males grow the larger and somewhat more colourful, and develop more produced (extended, pointed) trailing tips to the dorsal and anal fins, while ripe females are rounder-bodied. As with most of the genus, reliable sexing of unspawned juveniles is difficult without locality and breeding data.
Habitat
Cichlasoma boliviense is a fish of the western Amazon lowlands, specifically the upper Madeira drainage. Its documented range spans the Mamoré and Guaporé (Iténez) river basins and the Madre de Dios drainage, in Bolivia and adjacent Peru, with records also from the Bolivia–Brazil border reach of the Guaporé. These are the warm, low-gradient rivers and seasonally flooded plains of the Bolivian and Peruvian Amazon — the kind of country crossed by the Guaporé-Iténez and Mamoré freshwater ecoregions. The species does not seek out fast or rocky water; FishBase and field notes describe it inhabiting the shallow clayey portions of the shoreline and shallow, muddy-water pools, and Seriously Fish summarizes its biotope as shallow pools and slow-moving margins. In-situ water there is warm and on the harder side for an Amazon fish: FishBase lists a temperature band of roughly 73–81 °F and reports it from neutral to slightly alkaline, moderately mineralized water (pH around 7 and upward, hardness around 15 dH), reflecting the relatively sediment-rich, less acidic character of the upper Madeira's clay-bottomed habitats compared with the blackwaters farther downstream. Because it lives in shallow shoreline and pool habitat, its depth range is a shallow band of roughly the upper metre or two rather than open deep water.
Feeding
Like its congeners, Cichlasoma boliviense is a generalized benthic omnivore rather than a feeding specialist. FishBase places it at a trophic level near 3.0, the signature of a fish that takes a broad mix of small invertebrates, insect larvae, crustaceans, detritus and plant and algal material picked from the bottom and the structure of its shallow, muddy habitat. Working the clayey shorelines and pools it occupies, it forages over and through soft sediment, and in captivity it proves an undemanding, opportunistic feeder that readily accepts prepared foods alongside meatier items. There is no evidence of the dedicated sand-sifting of the eartheaters or of any piscivorous specialization; it is a middling, adaptable forager of the kind that does well precisely because it is not fussy. This dietary flexibility is part of why the species is widespread and apparently common within its range.
Mating
Detailed field observations of courtship in Cichlasoma boliviense specifically are scarce, but its behaviour follows the well-studied pattern of the genus and the closely allied 'Port cichlid' group. These are pair-bonding, territorial substrate spawners: a male and female form a bond, claim and defend a patch of bottom around a chosen spawning surface, and intensify in colour and posture as they ripen. The classic ethological work on the group — G. P. Baerends' detailed study of pre-spawning behaviour in the Port cichlid (published under the name Aequidens portalegrensis) — describes the lateral displays, jaw-locking tests of strength, and substrate-cleaning that structure pair formation in these fish, and boliviense can be expected to court in the same idiom. Aggression is real but moderate by Central American cichlid standards; pairs become more defensive around spawning, and a bonded pair will hold and patrol a territory together. Outside breeding the species is comparatively peaceable for a cichlid of its size.
Breeding
Cichlasoma boliviense is a biparental, open- or substrate-spawning cichlid, and although its reproduction has rarely been documented in the hobby, it conforms to the genus pattern, which is well known from relatives such as Cichlasoma dimerus and the Port cichlid. The pair cleans a firm surface — a flat rock, a broad leaf, a root or a pit in firm substrate — and the female deposits a sheet of adhesive eggs that the male fertilizes; both parents then share guard duty, the female typically tending and fanning the clutch while the male patrols the territory. Congeners lay on the order of a few hundred eggs per spawning (genus-typical), with the exact number scaling to female size. Eggs hatch in a few days, after which the wrigglers are commonly moved to one or more pits, and the free-swimming fry are guarded and herded by both parents for some weeks as a tight school — the substrate-guarding biparental care that is the hallmark of the cichlasomatine cichlids. As with related species, large water changes and warm, stable conditions on a rich, varied diet are the practical triggers that bring a settled pair into spawning condition.
In the aquarium
Cichlasoma boliviense is an uncommon aquarium fish — it appears in the hobby far less often than its relatives the black acara (Cichlasoma bimaculatum) or the Port cichlid, and is sometimes mislabelled with the ungrammatical 'boliviensis' (and should not be confused with the unrelated dwarf 'Bolivian ram,' Mikrogeophagus altispinosus). For anyone who does obtain it, it is a hardy, manageable medium cichlid. A bonded pair can be housed in a tank of around 90 × 38 × 12 in (roughly 25 US gal), though more room helps if it is to share space, and a footprint of four feet is more comfortable for a community.
It is not delicate about water chemistry. Reflecting its harder, near-neutral home waters, it does well anywhere from soft and slightly acidic to moderately hard and slightly alkaline — a practical range of about pH 6.5–7.5 and hardness up to roughly 15 dH suits it, at a temperature of about 73–81 °F. Good filtration and routine water changes matter more than chasing exact numbers. Flow should be gentle: this is a fish of slow shoreline pools, not rushing water, and strong currents are best avoided.
Décor should assume the fish will redecorate. Like most ground-oriented cichlids it digs and will rearrange substrate and uproot loosely planted plants, so use a sand or fine-gravel base, anchor or pot any plants (or choose tough, attached species such as Anubias and Java fern on wood), and provide rocks, roots and caves to break up sightlines and let fish stake out territories. Feeding is easy: a good cichlid pellet or flake as a staple, rounded out with frozen or live bloodworm, brine shrimp, chopped prawn, mussel and similar meaty treats, plus some vegetable content, keeps it in colour and condition.
Temperament is the main thing to plan around. Cichlasoma boliviense is less belligerent than many Central American cichlids but is still a territorial cichlid, especially around spawning. It is best kept either as a species-only pair or in a community of robust, medium-to-large tankmates — other similarly sized cichlids, sturdy characins and catfish — with enough cover that aggression is spread out rather than focused on one victim. It is unsuitable for a peaceful nano or planted show tank, and small, delicate fish may be eaten or harassed. Given space, stable warm water, a varied diet and structured décor, it is an undemanding and rewarding fish for a keeper who appreciates the understated, workmanlike acaras.
Conservation
Cichlasoma boliviense is assessed as Least Concern on the IUCN Red List (assessed 10 November 2020 by R. G. Frederico; published 2023). The assessment reflects a species that is widespread across the upper Madeira system — the Mamoré, Guaporé-Iténez and Madre de Dios drainages of Bolivia and Peru — apparently common within that range, and tolerant of a broad spread of water conditions and disturbed, sediment-laden habitats. The population trend is listed as unknown, and the species carries no CITES or CMS listing and is of no consequence to fisheries. No species-specific threats are flagged. As with the wider region, the long-term backdrop is the general intensification of pressure on Amazonian and upper-Madeira freshwaters — deforestation and agricultural sediment, gold-mining and its mercury, and hydropower development on the Madeira and its headwaters — but none of these is documented as a present danger to this adaptable, broadly distributed cichlid.