Taxonomy & naming
Albert Günther described this fish in 1867 as Heros longimanus, in his account of the fishes of Central America assembled from collections by Salvin, Godman and Captain J. M. Dow, with a fuller description and a plate following in 1868. The type locality is Lake Nicaragua, and the unique holotype (BMNH 1864.1.26.204) is held in the Natural History Museum, London. Like many nineteenth-century Central American cichlids, the species was long parked in the catch-all genus Cichlasoma (used by Villa, Bussing 1987, Conkel and others), then moved through a succession of homes as the great 'cichlasomine' assemblage was dismantled: Bussing's 1998 freshwater-fishes volume of Costa Rica treated it as Astatheros longimanus, while Kullander and Hartel placed it in Amphilophus, the combination under which most aquarists first met it. Allgayer (2010) briefly assigned it to Thorichthys. The current placement dates to the molecular and morphological revision of Middle American cichlids by Říčan, Piálek, Dragová and Novák (2016), who erected the genus Cribroheros for a cluster of lower-Central-American substrate-sifters formerly lumped in Amphilophus and Astatheros, and recombined the species as Cribroheros longimanus — a name since followed by González-Murcia et al. (2019), Angulo's Costa Rican checklists, and the Catalog of Fishes. One junior synonym is recognized: Cichlasoma popenoei Carr & Giovannoli, 1950, described from the Río Yeguare in Honduras and synonymized by Bussing & Martin (1975). Within Cribroheros the species sits in the rostratus species group alongside the long-snouted Cribroheros rostratus.
Morphology
Cribroheros longimanus is a moderately deep-bodied, laterally compressed cichlid of medium size. FishBase gives a maximum of about 5.5 in standard length (snout to tail base) for catalogued specimens; dominant aquarium males run a little larger, to roughly 6 in in total length, with most fish settling around 4.5 in. The ground colour is a pale sandy tan to greyish-olive, overlaid with rows of small dark spots and a variable pattern of vertical bars that the fish can switch on and off with mood — stressed or sparring individuals abruptly throw up bold black banding across the flanks, a useful field tell. The common name comes from the breeding livery: ripening fish, and males in particular, flush a warm orange to brick-red across the throat, breast and lower flanks, which is the 'pecho rojo' (red breast) that gives the species its Spanish vernacular. The specific name longimanus — 'long-handed' — refers to the elongate pectoral fins, which reach back nearly to the level of the anal fin. Sexual dimorphism is modest: males grow larger and develop heavier nuchal fullness and longer dorsal and anal fin extensions, while ripe females are deeper- and rounder-bodied. As with most Central American substrate-spawners, colour and barring are unreliable for sexing outside breeding condition.
Habitat
The red breast cichlid is one of the more widely distributed cichlids of lower Central America, recorded on both sides of the continental divide. On the Atlantic (Caribbean) slope it ranges from the Río Aguán in Honduras south through the Río Prinzapolka in Nicaragua to the Río San Juan drainage of Costa Rica, including the great lakes Nicaragua (its type locality) and Managua. On the Pacific slope it occurs from eastern Guatemala (the Río Nahualate) to north-western Costa Rica (the Río Bebedero), passing through El Salvador and Honduras; the Catalog of Fishes also notes an introduced population in Coahuila, Mexico. It is recorded from near sea level up to roughly 2789 ft in rivers, with the Nicaraguan checklist citing collections between about 6 and 1243 ft elevation. The species is ecologically flexible: in addition to the soft bottoms of Lake Nicaragua it inhabits rivers and streams, and although it is most abundant in slow or stagnant water it is also taken in strong current. Field accounts describe it in well-oxygenated, swift stretches over substrates of sand, pebbles, lava rock, wood and leaf litter, sometimes near waterfalls. In-situ and reference water chemistry runs hard and near-neutral to alkaline — FishBase cites pH 7.0–8.0, hardness 5–20 dH, and a broad temperature tolerance of about 73–97 °F — placing it firmly among the warm, mineral-rich waters of the Pacific and Caribbean lowlands rather than the soft blackwaters of South America.
Feeding
Cribroheros longimanus is a benthic substrate-sifter, sitting low on the food web at an estimated trophic level near 2.7. It works soft bottoms by taking mouthfuls of sand and fine sediment, sorting edible material and expelling the rest through the gills and mouth in the winnowing manner that defines the genus — indeed the name Cribroheros, from Latin cribrum ('sieve'), was coined for exactly this feeding mode. Gut and field studies report it browsing soft bottoms for aquatic insects, with dipteran (midge and chironomid) larvae prominent in the diet; in practice it is an opportunistic omnivore with a carnivorous lean, also taking other small benthic invertebrates and organic detritus. In the river and lake communities it occupies, it functions as a generalist forager of the sand and leaf-litter zones, and in the aquarium it accepts a wide range of prepared and live foods without difficulty.
Mating
Like its Central American relatives, the red breast cichlid forms monogamous pairs and is a substrate-brooder, so reproduction is organized around a jointly defended territory rather than a lek or harem. It is a territorial fish with a strong character: outside breeding it tolerates company in a large space, but a pair preparing to spawn becomes pointedly intolerant of intruders near the chosen site, and rival males in confined quarters will not abide one another — confrontations between two dominant males can escalate to sustained fighting and, in a tank too small to allow escape, to the death of the loser. Pair formation follows the familiar cichlid pattern of lateral displays, jaw-locking trials of strength and substrate-cleaning, the partners testing one another before committing to a nest site. The heightened red breast colour and the ability to flash dark vertical bars both play into these courtship and threat displays.
Breeding
Cribroheros longimanus is a biparental open-substrate spawner: the pair cleans a flat rock, log or pit and the female deposits her eggs on the exposed surface, where both parents guard and tend the clutch and, after hatching, herd and defend the free-swimming fry. Hobbyist reports describe a mature female carrying hundreds of small eggs (on the order of 0.5 in in diameter, comparable to those of the related Cribroheros rostratus), with the eggs laid in adhesive sheets and fanned by the female while the male patrols the territory perimeter — the classic division of labour for the genus. No detailed wild fecundity figure is published for this species; a clutch in the low hundreds of eggs is genus-typical for these medium-sized Cribroheros substrate-spawners. In aquaria it has been bred without great difficulty once a compatible pair is established, with spawning reported around 77 °F and pH near 7.5; the principal obstacle is pairing itself, given the species' readiness to turn aggression on a mismatched or crowded partner. Parental care is biparental and extended through the early free-swimming stage in the manner usual for Central American open-spawners.
In the aquarium
The red breast cichlid is a robust, tolerant aquarium fish that has been kept and bred for decades, though it is best regarded as a moderately aggressive Central American rather than a community fish. A single pair needs a footprint on the order of 130 US gal, and more if kept with tankmates, so that territories can be spaced and weaker fish can retreat — undersized tanks are the usual cause of fighting and losses. Because the species ranges into fast, well-oxygenated rivers, it does best with brisk water movement and generous, over-specified filtration; strong flow and high dissolved oxygen suit it, and it shows none of the soft-blackwater requirements of South American eartheaters. Water should be kept hard and near-neutral to slightly alkaline (roughly pH 7–8, moderate hardness) at a warm 75–86 °F, mirroring its Pacific and Caribbean lowland habitats.
The single most important furnishing is an open sand bottom: this is a compulsive digger that sifts and rearranges substrate constantly, so fine sand spares its gills and lets it forage naturally, and any planting needs to be potted, weighted or wedged among rocks and roots, since loose plants will be uprooted. Scattered smooth rocks, driftwood and a few flat stones give pairs both cover and spawning sites. Diet is undemanding — a varied menu of quality cichlid pellets and flake, supplemented with frozen and live foods such as bloodworm, brine shrimp and small crustaceans, keeps the fish in colour and condition; bottom-feeding behaviour means sinking foods are taken readily.
Compatibility is the real consideration. The species is territorial and intolerant of conspecific males, so keeping multiple males in one tank is strongly discouraged, and even a bonded pair will hold and defend a spawning territory firmly. Suitable companions are similarly sized, robust Central Americans and other sturdy fish that can hold their own without being bullied, housed in a tank large enough to partition space; timid or much smaller fish are a poor match. As with most of its relatives, the safest route to breeding is to grow on a group of young fish and let a pair form naturally, then be ready to separate a partner that the dominant fish turns on.
Conservation
The IUCN Red List assesses Cribroheros longimanus as Least Concern (assessed 24 May 2019 by T.J. Lyons and W.A. Matamoros, published 2020), citing its wide distribution across the lowlands of Guatemala, El Salvador, Honduras, Nicaragua and Costa Rica and a population judged to be stable. It carries no CITES or CMS listing and is harmless to people. As a widely distributed, ecologically flexible generalist — at home in lakes, slow backwaters and fast rivers alike, across a broad span of elevation and water chemistry — it is far less exposed than the many narrow-range endemics of the region, several of them confined to single Nicaraguan crater lakes. No species-specific threats are flagged in the assessment. The broader backdrop for Central American freshwater fishes nonetheless includes deforestation and agricultural runoff, river damming and water extraction, pollution and the spread of introduced species; the established population in Coahuila, Mexico, is itself an example of how readily Central American cichlids move beyond their native range when transported.