Taxonomy & naming
Amphilophus chancho was described in 2008 by Jay R. Stauffer Jr., Jeffrey K. McCrary and Kara E. Black, in a paper titled 'Three new species of cichlid fishes (Teleostei: Cichlidae) from Lake Apoyo, Nicaragua' in the Proceedings of the Biological Society of Washington (volume 121). It was one of three Apoyo endemics named together in that paper, alongside Amphilophus astorquii and Amphilophus flaveolus. Those three joined the earlier Amphilophus zaliosus and the later Amphilophus globosus and Amphilophus supercilius to make up the Apoyo species flock. The holotype (PSU 4514.1) was taken at Granada Bajadero, on the lake's northern shore. The species sits within the Amphilophus citrinellus complex — the 'Midas cichlid' radiation of the Nicaraguan lakes and crater lakes — inside the heroine cichlids of subfamily Cichlinae. The Catalog of Fishes lists it as valid, and FishBase and the IUCN recognise it under the same name. The specific epithet is not classical Latin or Greek but the vernacular Nicaraguan Spanish word chancho, 'pig' or 'hog' — the name local fishermen use for this heavy-bodied, bottom-rooting fish, which the describers kept.
Morphology
Amphilophus chancho is among the larger members of the Apoyo flock, reaching about 9.5 in standard length (FishBase). It has the typical Midas build: robust, deep-bodied and laterally compressed. What separates it from its Apoyo congeners is a combination of traits rather than one dramatic feature — the describers told the three 2008 species apart mainly by body depth, head profile, gill-raker counts and the form of the pharyngeal jaw. Ground colour in life runs grey to greenish or olive, usually with a darker mid-lateral bar or blotching that flushes up under stress and breeding. As in other Midas-complex cichlids, a minority of fish are 'gold' (amelanistic) morphs in orange or pink, but the barred grey form predominates. Being a citrinellus-complex fish, it can develop the genus-typical nuchal hump on the forehead, most pronounced in dominant breeding males. Its mouth is moderately sized and its lips are not conspicuously enlarged, which sets it apart from the thick-lipped Midas relatives elsewhere in the lake system. Sexual dimorphism follows the usual Amphilophus pattern: males grow larger and heavier-headed, while ripe females are smaller and rounder.
Habitat
The chancho cichlid is endemic to Laguna de Apoyo, a volcanic crater lake of about 21 square kilometres just south-east of Granada, Nicaragua — the only place it occurs. Apoyo is a maar-type caldera lake: deep (over 574 ft), warm, clear and somewhat alkaline, and cut off from the surrounding drainage. It was colonised relatively recently in geological time by a single Midas-cichlid lineage out of the great Nicaraguan lakes, and its handful of endemic Amphilophus all trace back to that founding population. Within the lake, Amphilophus chancho keeps to rocky areas, where the describers recorded it nesting in dug-out or adapted pre-existing holes among rocks at depths of roughly 7–82 ft — a deeper, more rock-bound niche than the shallow sand-nesting Amphilophus flaveolus it shares the lake with. The water is hard and alkaline by Central American standards, running around pH 7.5–9 and staying comparatively warm year-round, roughly 79–86 °F, a reflection of the lake's volcanic chemistry. Its entire range falls within the San Juan freshwater ecoregion (FEOW 205).
Feeding
Amphilophus chancho is a generalist omnivore of the rocky lake bottom. FishBase places it at trophic level about 3.3, a figure estimated from its size and close relatives rather than from a dedicated gut-content study. That is consistent with a diet of benthic invertebrates, small organisms and plant and detrital matter gathered from and around the rocks it lives among. Within the Apoyo flock, niche partitioning is part of what let the endemics diverge: relatives such as Amphilophus zaliosus shifted to open-water, limnetic feeding, while the deeper-bodied benthic species like the chancho worked the bottom. Its robust body, moderate mouth and rooting, hole-dwelling habit all fit a fish that forages over and within rocky substrate rather than chasing prey in open water or sifting sand. As in the other Midas-complex cichlids, its pharyngeal jaws are adaptable, and the flock as a whole spans a range of jaw shapes suited to harder or softer foods.
Mating
Like all Midas-complex cichlids, Amphilophus chancho is a biparental, pair-bonding substrate spawner, and pair formation lies at the heart of its story. The 2008 describers stressed that the Apoyo endemics are reproductively isolated from one another by assortative mating — fish pair preferentially with their own kind — the mechanism that keeps the flock distinct even though several species live side by side in one small lake. A bonded male and female form a pair, choose and prepare a nest site, and defend a territory around it together. Courtship is the standard Amphilophus repertoire: lateral displays, fin-spreading, quivering and joint site-cleaning, with the breeding fish taking on intensified, higher-contrast colours. Because Amphilophus chancho nests in holes among rocks rather than on open sand, the pair's territory centres on a defended cavity that both fish guard hard through the spawning cycle.
Breeding
Amphilophus chancho is a cave- or hole-nesting biparental substrate spawner, and that habit is what most clearly separates it from its sand-nesting Apoyo relative Amphilophus flaveolus. The describers recorded it nesting in dug or adapted pre-existing holes in rocky areas at 7–82 ft depth, where the adhesive eggs are laid on the cavity wall or floor and both parents share the work: the female concentrates on fanning and tending the clutch, while the male patrols and defends the surrounding territory. After hatching, the wrigglers stay in the nest hole; once free-swimming, the fry are herded and guarded as a school by both parents, as they are throughout the genus. Clutch counts for wild fish are not published, but Midas-complex cichlids of comparable size typically lay broods of several hundred eggs, and care is prolonged, with both adults defending eggs, larvae and free-swimming young. As in many crater-lake cichlids, breeding tracks the favourable season, and a pair in condition will spawn again and again.
In the aquarium
Amphilophus chancho is essentially a fish of scientific rather than commercial interest, and it is very rarely seen in the hobby. What husbandry guidance exists is extrapolated from the well-known Midas and red-devil cichlids (Amphilophus citrinellus, Amphilophus labiatus) and from the lake's measured conditions.
Tank: this is a large, robust, territorial fish, so give it a big footprint to match a 9.5 in digging cichlid — on the order of 65 US gal or more for a single fish, and considerably more for a pair with tankmates. It needs a substrate it can excavate and a rockwork layout that provides the caves and holes it naturally nests in.
Water: track Apoyo's hard, warm, alkaline chemistry — temperature around 79–86 °F and a distinctly alkaline pH, roughly 7.5–8.5 — with strong filtration and regular water changes to keep up with a messy, substrate-moving fish.
Feeding: straightforward for an omnivore. Quality sinking pellets, supplemented with frozen and live invertebrates and some vegetable matter, suit its natural mixed diet.
Tankmates: temperament is the main caution. Like its Midas relatives it is powerful and territorial, especially around a nest, so companions must be similarly robust and the tank large enough to dissipate aggression; a breeding pair will hold and defend a substantial territory. Given its rarity and its conservation status, the species matters far more in the wild than as an aquarium subject, and it is best regarded as a specialist's fish, not a general community cichlid.
Conservation
Amphilophus chancho is listed by the IUCN Red List as Critically Endangered (assessed 15 July 2019). The reason is bound up with what makes it remarkable: it is a single-lake endemic, confined to Laguna de Apoyo and nowhere else, so its entire global population sits in one small crater lake of about 21 square kilometres. That extreme range restriction leaves it acutely exposed to any lake-wide disturbance. The documented threats to Apoyo's endemic cichlids include introduced non-native fishes — tilapia in particular have been put into the lake and compete with and prey on native species — along with pollution and nutrient loading from shoreline development and tourism, water abstraction, and the general strain on a closed crater-lake ecosystem with no refuge population elsewhere. The Apoyo flock as a whole, several of whose members are likewise Critically Endangered, is a conservation priority precisely because each species lives in only this one body of water: a loss of Apoyo's water quality, or an invasion by non-natives, would threaten all of them at once. The species carries no CITES listing.