Taxonomy & naming
The black belt cichlid was described by the British ichthyologist Charles Tate Regan in 1905 as Cichlasoma maculicauda, in his sweeping revision of the American cichlid genus Cichlasoma and its allies, published in the Annals and Magazine of Natural History. Like most of the Middle American 'Cichlasoma' of that era, it spent more than a century as a member of that catch-all genus before the modern unravelling of the group. It was moved through Paraneetroplus and at times allied with Theraps and Heros before being placed in Vieja, a genus erected by Fernández-Yépez in 1969 — the type species of which, Vieja panamensis Fernández-Yépez, 1969, was later shown to be this same fish and now falls into synonymy. Several other names join it there: Cichlasoma nigritum Meek, 1907 (described from Lake Nicaragua), and Cichlasoma globosum and Cichlasoma manana, both Miller, 1907, from Guatemala. The most recent comprehensive treatment of the Middle American 'herichthyin' cichlids, McMahan, Matamoros, Piller and Chakrabarty (2015, Zootaxa), retained maculicauda in Vieja and pared the genus to a smaller, better-supported set of species; it sits in the Neotropical subfamily Cichlinae within the heroine cichlids (the tribe is variously rendered Therapsini or Heroini). Within Vieja the species is diagnostic: it is distinguished from its congeners by a large dark, round blotch filling the caudal peduncle, through which the lower lateral line runs, with that blotch not extending forward onto the body — a feature that, combined with its broad mid-body bar, makes it hard to confuse with anything else in the genus.
Morphology
Vieja maculicauda is a stout, laterally compressed cichlid that reaches about 10 in in standard length (Kullander 2003); aquarium specimens are commonly cited as fully grown at roughly 10–12 in total length, with reports up to around 14 in for exceptional fish. Wild populations in Guatemala's Lago de Izabal / Río Dulce system, which support a longstanding local fishery, include exceptionally large individuals reported to about 14 in total length and roughly 1.4 kg (3 lb) — among the largest documented for the species, and a reminder that field maxima can exceed typical aquarium-fish figures. The body is tall and robust with the steep forehead typical of the genus, and mature males develop a pronounced nuchal hump. Two markings define it. The first is a broad, dark vertical bar that drops across the middle of the flank — the 'belt' of the common name, a feature no other Vieja shows so strongly. The second is a large, round black blotch that fills the caudal peduncle at the base of the tail, with the lower lateral line passing through it; this blotch stops at the peduncle and does not run forward onto the body, which separates maculicauda from its relatives. Ground colour ranges from pearly grey through olive to dusky, often suffused with pink or iridescent flecks, and the throat and lower head frequently flush a striking red or orange — the origin of trade names such as 'boca colorada' (red mouth). Sexual dimorphism is modest: males grow larger, carry the stronger nuchal hump and tend to be more intensely coloured, while ripe females are deeper-bodied; aquarists also report that females can appear darker overall. Juveniles are plainer and silvery, the belt and caudal blotch sharpening with age.
Habitat
The black belt cichlid is a fish of the Atlantic (Caribbean) slope of Central America, distributed through the lowland reaches of rivers from the Usumacinta drainage of Guatemala and southern Mexico south through Belize, Honduras, Nicaragua and Costa Rica to the Río Chagres in Panama — an unusually broad range that crosses several major geological boundaries (the Maya and Chortís blocks, the Costa Rica–Panama arc and the Isthmus of Panama), a pattern that has made the species a subject of biogeographic interest (McMahan et al. 2017). It occupies low-gradient, slow-moving habitats: the extreme lower valleys of rivers, freshwater-to-brackish streams, canals, coastal lagoons, swamps and mangrove-fringed estuaries, typically over muddy and sandy bottoms among submerged trees and logs and along shaded banks. Its defining ecological trait is salinity tolerance — it is strongly euryhaline, common in brackish estuaries and recorded across limnetic, oligohaline, mesohaline and even polyhaline conditions; through the Panama Canal it was found established in the Miraflores Third Lock Lake at 6–14 PSU, and it passed between oceans via the canal as one of the few cichlids able to do so. FishBase reports a tropical temperature range of about 79–82 °F in the field and a depth range from roughly 33 ft upward, though the species is most associated with shallow, sluggish shoreline water; in-situ measurements give a near-neutral to alkaline, hard-water profile consistent with its lowland, often calcareous and estuarine habitats. Field collectors report the fish can thrive even in full seawater on occasion — the most extreme expression of its salinity tolerance. A documented freshwater-to-brackish capture site on the Guatemalan shore of Lago de Izabal (Marimonte, near the Río Dulce outlet) measured pH 7.8–8.2 at about 79 °F, and a single seine haul there also took eight other cichlids alongside the black belt — Thorichthys aureus, Archocentrus spinosissimus, A. spilurus, 'Nandopsis' octofasciatus, 'N.' managuensis, 'N.' salvini and Amphilophus robertsoni — a measure of how crowded with cichlid species the lowland Caribbean-slope waters of Central America can be.
Feeding
Vieja maculicauda is, like most of its genus, predominantly herbivorous and detritivorous. FishBase places it at a low trophic level (about 2.0) and describes it feeding on benthic detritus composed of vegetable matter — both aquatic and terrestrial plants — together with seeds and fruits that fall into the water. Field studies of cichlid assemblages in Belize and elsewhere (Winemiller, Kelso-Winemiller & Brenkert 1995; Cochran-Biederman & Winemiller 2010) found its diet dominated by algae, macrophytes and plant detritus, supplemented by small molluscs and other invertebrates — an omnivore with a strong plant bias rather than a strict vegetarian. Its powerful jaws let it tear off bite-sized pieces of vegetation, and in the wild it works the soft sediment and submerged wood of slow lowland water for plant material, fallen fruit and the invertebrates living among it. In the riverine community it functions as a large-bodied grazer and detritus processor of the lower-gradient reaches rather than a predator of other fishes.
Mating
The black belt cichlid forms monogamous pairs and is a territorial substrate spawner. It is reasonably peaceful toward its own kind outside breeding but becomes markedly more aggressive as a pair forms and a spawning site is claimed, with both partners defending a territory. Pair formation can be combative: males will spar with one another, and a male may harass a female that is unwilling to spawn, so well-matched, mutually willing partners are important. As in many large heroine cichlids, courtship involves lateral displays, mouth-wrestling and joint clearing and inspection of a hard surface that will serve as the spawning site. The strengthening of the throat and body colour, and the deepening of the female's body as she ripens, accompany this pre-spawning phase.
Breeding
Vieja maculicauda is a biparental, open-substrate spawner. The pair cleans a flat hard surface — a rock, root or similar — and the female lays her eggs on it in the open rather than in a cave; FishBase characterises the species as spawning in open water and producing on the order of 600–1,000 fry per spawning, with both parents sharing the care of the brood. Eggs typically hatch in two to three days, after which the wrigglers are moved to pits excavated in the substrate, and the free-swimming fry are then led about and guarded vigorously by both parents, who become highly protective and intolerant of intruders. The young take newly hatched brine shrimp and other small foods as they grow. In aquaria the species breeds relatively readily once a compatible pair has settled and a suitable flat spawning surface and digging substrate are provided; the main obstacle is not fecundity but the management of the pair's aggression, which peaks while they are guarding eggs and fry.
In the aquarium
The black belt cichlid is a long-established, if somewhat overlooked, large-cichlid for the hobby — a handsome centrepiece fish that is not difficult to keep for an aquarist prepared for its size and temperament. It has been in the trade since the early 1970s, one of a wave of new Central American cichlids first exported to hobbyists from collecting expeditions along the Caribbean coast of Belize and Honduras. Because adults reach 10–12 in, a single fish or pair needs a large tank: a footprint on the order of 75 US gal is a common minimum for one adult, and a pair or a community of large tankmates calls for considerably more. The species is undemanding about water chemistry, reflecting its tolerance of everything from soft fresh water to brackish estuaries; a near-neutral pH (around 7.0), or anywhere in the broad 7–8 range, suits it well, with temperatures of roughly 75–82 °F. Filtration should be generous and water changes regular, as these are large, messy feeders, but strong current is unnecessary and even unwelcome — they are fish of slow water, so returns are best aimed to break the surface for gas exchange rather than to create flow.
Use a sand or fine substrate, since the fish like to dig, and furnish the tank with rockwork, roots and driftwood that provide cover and break up lines of sight; subdued lighting, helped by floating plants, suits a species that dislikes bright illumination. Rooted aquarium plants are generally a lost cause — Vieja are notorious among large cichlids for tearing up and eating vegetation — so any greenery is best regarded as food or kept to tough, potted or floating species. Feeding is straightforward: a varied diet built around vegetable matter (spirulina or other green foods, blanched greens) with meatier supplements such as bloodworms, brine shrimp and quality pellets keeps them in good colour and condition; their plant bias should be respected even though they take prepared and frozen foods eagerly.
Temperament is the chief consideration. Outside breeding the black belt is relatively even-tempered for its size, but it is feisty toward conspecifics and will treat anything small enough to swallow as food, so tankmates should be similarly large and able to hold their own — robust Central American cichlids of comparable size, or the larger catfishes and characins that share its native rivers, are sensible choices. Aggression spikes during spawning, when a pair guarding eggs or fry becomes intensely protective and may dominate even a big aquarium; a roomy tank with sightline breaks, and the readiness to separate combatants, are the usual safeguards. Inexperienced keepers most often come to grief by underestimating the adult size and the breeding-season aggression rather than by any fussiness in the fish itself.
Conservation
The IUCN Red List assesses Vieja maculicauda as Least Concern (assessed 27 August 2018 by T.J. Lyons; published 2019), with the population trend recorded as unknown. The listing reflects the species' very wide distribution across the Caribbean slope of Central America and its tolerance of a broad range of habitats and salinities, which together make it far less vulnerable than the many narrow-range endemics of the region. It carries no CITES listing and is not considered a threat to humans. The fish is used locally for food and is harvested commercially — a fishery documented, for example, around Aqua Dulce on Guatemala's Río Dulce, where dozens of local families have long fished black belt cichlids for the market — including some aquaculture, as well as being collected for the aquarium trade, but none of these is flagged as a population-level concern. As with other widespread lowland Central American fishes, the broader pressures on its habitat are the familiar ones — coastal and lowland development, deforestation, pollution and the alteration of river flow — but the black belt cichlid's adaptability, especially its ability to occupy brackish and disturbed waters, leaves it comparatively secure. It has also turned up occasionally outside its range as an aquarium release (single records in the United States and Puerto Rico), without establishing.