Taxonomy & naming
The green guapote was described by the great American ichthyologist David Starr Jordan in 1889 as Heros beani, honouring his colleague Tarleton Hoffman Bean of the U.S. National Museum. Like nearly every Central American heroine it spent most of the following century lumped into the genus Cichlasoma, and was later treated under Nandopsis and Cichlasoma (Nandopsis) before the wholesale revision of Middle American cichlids. The genus Mayaheros was erected by Říčan, Piálek, Dragová & Novák in 2016 for the Mayan-cichlid group, and molecular phylogenetics placed beani firmly with Mayaheros urophthalmus as its sister, despite their geographic separation on opposite slopes of Mexico; the Catalog of Fishes (Fricke, Eschmeyer & Van der Laan) accordingly lists it as Mayaheros beani (Jordan 1889). It is one of only two universally accepted species in the genus, the other being the urophthalmus complex itself, and its validity has never been in doubt — unlike the contested Yucatán micro-endemics, beani is a distinct, well-characterized Pacific-slope lineage.
Morphology
Mayaheros beani is the largest member of its genus, reaching about 12 in total length and a robust, deep-bodied build heavier than the more elongate Mayaheros urophthalmus. The ground colour is a brassy olive-green to greenish-gold — the source of the 'green guapote' name — often with iridescent flecking and a series of darker vertical bars across the flanks that can be intensified or hidden with mood. Like all Mayan cichlids it carries the diagnostic dark ocellus (eyespot) on the upper caudal peduncle, frequently with a pale ring, and dark markings or a broken midlateral stripe along the side. The head is large with a steep forehead and a strong, slightly protrusible mouth set with conical jaw teeth, the equipment of a generalist predator. Sexual dimorphism is moderate: dominant males grow larger, deeper-headed, and may develop a slight nuchal hump and longer trailing dorsal- and anal-fin tips, while females stay smaller and rounder-bellied. Breeding fish darken and their bars and ocellus stand out sharply.
Habitat
Uniquely among the Mayan cichlids, Mayaheros beani occupies the Pacific slope of Mexico, in the rivers and associated lagoons of Sinaloa and neighbouring states draining to the Gulf of California — the Río Fuerte, Río Sinaloa, Río Culiacán and similar systems. It is a fish of warm lowland rivers, slow reaches, oxbows, floodplain lagoons and estuarine margins, and like its relatives it is euryhaline, tolerating brackish water in coastal lagoons and river mouths. These north-western Mexican rivers are seasonal, swelling with summer rains and shrinking through the dry season, and the species copes with the attendant swings in flow, turbidity and salinity. Reported water conditions are warm and hard: temperatures around 73–86 °F and alkaline, mineral-rich water (pH from about 7.5 upward). A population was historically introduced and established in irrigation systems of southern California but has since been extirpated, leaving the species native only to its Pacific Mexican range.
Feeding
The green guapote is a generalist predator and omnivore. Its build — a large mouth, strong conical teeth and a powerful pharyngeal apparatus — equips it to take a broad diet of small fish, crustaceans (including shrimp and crabs in the lower rivers and lagoons), aquatic and terrestrial insects, snails and other invertebrates, supplemented with plant material and detritus. As one of the larger predators in its river systems it occupies a relatively high position in the local food web and is valued by fishers precisely because it grows to a good size on this mixed carnivorous diet. The euryhaline habit means it exploits both freshwater prey upstream and estuarine invertebrates and small fishes near the coast.
Mating
Like the rest of its genus, Mayaheros beani is a monogamous, biparental, strongly territorial breeder. Pairs form, select and clear a spawning site, and defend a territory around it with vigorous lateral displays, fin-flaring and jaw-locking against rivals; the species is notably pugnacious when in breeding condition. Spawning is tied to the warm season — in the seasonal Pacific rivers this means the summer wet months, when temperatures are high and food is plentiful, allowing the pair to raise a brood under favourable conditions. Courtship follows the heroine template of mutual displays and substrate-cleaning before the female deposits eggs and the pair settles into shared guard duty.
Breeding
Mayaheros beani is an open substrate spawner. The pair lays adhesive eggs in neat rows on a cleaned hard surface — a flat rock, submerged log or firm patch of substrate — and both parents tend the clutch: the female typically fans and cleans the eggs while the male patrols the perimeter, with the roles shared during brood care. As a large female, a ripe beani can produce a substantial clutch (the genus ranges from a few hundred to over a thousand eggs with female size), and the eggs hatch within a few days in warm water. Wrigglers are moved to pits, and once free-swimming the fry are herded as a dense school and guarded by both parents for several weeks. The species is reported to spawn readily in captivity given a compatible pair and adequate space, following the same dependable biparental pattern that makes Central American heroines popular among keepers who enjoy parental behaviour.
In the aquarium
The green guapote is an established, if specialist, aquarium fish — a 'big American cichlid' for keepers with the space and tolerance for an aggressive species. At up to 12 in it needs a large tank: a single adult or a proven pair should have at least 120 US gal (around 120 US gallons), with more strongly preferred, furnished with an open sandy floor, large rocks and driftwood arranged to break sightlines and define territory. Water should mirror its hard, warm, alkaline rivers — pH 7.5-8.5, moderate-to-high hardness, temperature 75–82 °F — and it tolerates a little salt. Robust filtration and regular large water changes are essential for a big, messy, high-protein feeder. Diet is easy: quality cichlid pellets as a base, plus frozen and live foods such as shrimp, earthworms and the occasional piece of fish or mussel; vegetable matter rounds it out. The defining husbandry issue is temperament — green guapotes are territorial and become genuinely combative when breeding, so tankmates must be similarly large and sturdy (other big Central Americans), and many keepers ultimately house a pair alone. It is not a community fish and not a beginner's fish, but for someone equipped for a large, characterful predator it is rewarding and long-lived.
Conservation
The IUCN Red List assesses Mayaheros beani as Least Concern (assessed 24 August 2018), reflecting a reasonably wide distribution across several north-western Mexican river systems and a population that supports local fisheries without evident decline. It carries no CITES listing. As a valued food and game fish it is harvested, but at a level the assessment does not flag as a population threat. The longer-term pressures on its habitat are the familiar ones for seasonal Pacific-slope Mexican rivers: dam construction and water abstraction for the region's intensive irrigated agriculture, which alter flow regimes and fragment populations; pollution and sedimentation from farming; and the spread of introduced fishes, particularly African tilapias, throughout these drainages. None is documented as an acute danger to the green guapote specifically, but they form the backdrop against which a hardy but range-limited Pacific endemic should be watched.