Taxonomy & naming
The fish was described by the American ichthyologist Carl L. Hubbs in 1938 as Cichlasoma ericymba, in the second of his Carnegie Institution papers on the fishes of the Yucatán Peninsula. The type material came from the San Bulha cenote at Mérida, Yucatán, Mexico — one of the water-filled limestone sinkholes that are the region's signature freshwater habitat; the holotype (UMMZ 116091) and a paratype are held at the University of Michigan Museum of Zoology. The epithet ericymba, from Greek roots meaning roughly 'of the hollow/cavern,' alludes to this cenote origin. For most of the twentieth century the species sat in the catch-all genus Cichlasoma, listed by Kullander (2003) as incertae sedis pending revision. The genus Mayaheros was erected by Říčan, Piálek, Dragová & Novák in 2016 to hold the Mayan-cichlid group, and the Catalog of Fishes (Fricke, Eschmeyer & Van der Laan) accordingly lists it as Mayaheros ericymba (Hubbs 1938). Its validity is the central question. Catalog of Fishes retains it only because it has never been directly checked against urophthalmus; the geometric-morphometric and molecular survey of Yucatán Mayan cichlids by Mejía and colleagues (Copeia 2018) found the named cenote forms to be phenotypic variants rather than separate lineages, and several sister names from the same era — conchitae, mayorum, zebra and others, also described from Mérida-area cenotes — have since been synonymized with urophthalmus outright. Mayaheros ericymba thus persists as a nominally valid but unverified species, a name awaiting a formal revision.
Morphology
Mayaheros ericymba is a small-to-modest heroine cichlid, maturing well under the robust 12 in-plus reached by Mayaheros urophthalmus; FishBase and the type series point to a fish on the order of 4–5 in. The body is the typical oval, laterally compressed heroine shape, with a brassy-tan to olive ground colour overlaid by the lateral barring and dark flank markings characteristic of the Mayan-cichlid group. The diagnostic feature of the group is the conspicuous ocellus — a black, pale-ringed eyespot — high on the caudal peduncle, the 'tail-eye' (Greek oura + ophthalmos) that gives the parent species its name urophthalmus. Several dark vertical bars cross the flanks and can be flashed or suppressed with mood. Sexual dimorphism is slight throughout the genus: males average a little larger and develop somewhat longer dorsal- and anal-fin tips, while ripe females are deeper-bellied, with no dramatic colour difference. Because ericymba has scarcely been studied apart from its original description, fine meristic and colour detail beyond the group-typical pattern is not well documented; Hubbs distinguished his cenote forms on subtle differences in body proportion, fin counts and coloration that later workers have found to fall within the range of variation of a single species.
Habitat
The species is known from cenotes near Mérida, in the karst lowlands of the northern Yucatán Peninsula on the Atlantic slope, where surface water is scarce and most freshwater is held in cenotes — collapsed limestone sinkholes opening onto the aquifer. The type San Bulha cenote is exactly this kind of habitat: a warm, clear-to-turbid groundwater pool in limestone terrain, fed by the regional water table and largely buffered from the sharp seasonal swings that affect surface aguadas. Like the rest of the Mayan-cichlid group, ericymba is a euryhaline generalist tolerant of the hard, mineral-rich, alkaline waters typical of the Yucatán's limestone aquifer; the group as a whole ranges from fresh through brackish to nearly marine conditions in coastal lagoons. Cenote water is warm (commonly mid-to-upper 20s °C), very hard and alkaline (pH well above 7), and often remarkably stable in temperature year-round. The species' apparent micro-endemism to a few Mérida cenotes is at least partly an artifact of how cenote faunas were sampled; the broader group occupies the entire peninsula, and cenote populations are connected through the shared aquifer.
Feeding
No dedicated diet study exists for Mayaheros ericymba, but its membership in the Mayan-cichlid group places it among opportunistic omnivores with a carnivorous lean. Mayaheros urophthalmus, the best-studied member, is a generalist predator-omnivore taking small fish, crustaceans, aquatic and terrestrial insects, snails, detritus and some plant material, shifting its diet readily with what each habitat offers. In a cenote — a comparatively food-poor, enclosed groundwater pool — ericymba would be expected to work the bottom and walls for insect larvae, microcrustaceans, snails and organic debris washed in from above, taking small fish and terrestrial invertebrates when they fall in. The robust heroine jaw and pharyngeal mill suit a mixed diet that includes hard-shelled prey. Trophically the group sits in the mid-range of the food web as a flexible secondary consumer, a generalism that lets it persist in the patchy, resource-limited cenote habitat.
Mating
Reproductive behaviour has not been documented specifically for Mayaheros ericymba, but the Mayan-cichlid group is uniformly biparental and strongly territorial when breeding. In Mayaheros urophthalmus, pairs form a monogamous bond, clear and defend a substrate territory, and become markedly aggressive toward intruders during courtship and brood care; spawning is timed to the warm season when temperatures are reliably above about 75 °F and food is abundant. A pair courts with lateral displays, fin-spreading and substrate-cleaning over a chosen surface. There is every reason to expect ericymba follows the same template — a monogamous pair holding and defending a territory — though in the thermally stable, food-limited cenote environment spawning may be less sharply seasonal than in surface waters, with broods produced whenever a pair is in condition and a defensible site is available.
Breeding
As with mating, breeding is undocumented for Mayaheros ericymba itself and is inferred from the group. Mayan cichlids are open substrate spawners: the pair lays adhesive eggs in rows on a cleaned hard surface — a flat stone, ledge of rock, root, or firm patch of substrate — and both parents guard the clutch, fanning the eggs and later shepherding the free-swimming fry. Clutch sizes in Mayaheros urophthalmus run from a few hundred to over a thousand eggs depending on female size; eggs hatch in a few days at warm temperatures, and the wrigglers are moved to pits before becoming free-swimming. Parental care is extended — the pair guards the school of fry for several weeks, and the group is documented producing multiple broods through a long warm season. A small-bodied cenote form such as ericymba would lay a correspondingly smaller clutch, but the biparental, multiple-brood substrate-spawning pattern of the group is almost certainly retained.
In the aquarium
Mayaheros ericymba is essentially absent from the aquarium hobby as a named fish — it is not collected or traded under its own name, and what reaches keepers as 'Mayan cichlid' is overwhelmingly Mayaheros urophthalmus. Any husbandry guidance is therefore by extension from its better-known relatives, which are hardy, undemanding, and well suited to keepers who can manage their aggression. A pair would want a tank on the order of 55 US gal or more with an open sandy bottom, scattered rock and wood for cover and territory boundaries, and the very hard, alkaline water of its cenote home (pH comfortably above 7, high hardness, temperature around 77–82 °F); the group tolerates a touch of salt and copes with a wide chemical envelope. The standing caution for the whole Mayan-cichlid group applies: they are robustly territorial and become genuinely combative when spawning, so tankmates must be sturdy and the tank large enough to defuse aggression. Feeding is trivial — they accept pellets, frozen and live foods readily. None of this is specific to ericymba, and a keeper should treat the name as a poorly-defined cenote member of the urophthalmus complex rather than a distinct aquarium fish.
Conservation
Mayaheros ericymba has not been assessed in its own right by the IUCN Red List; the conservation evaluations in this group treat the Mayan cichlid as the single widespread species Mayaheros urophthalmus (assessed Least Concern), reflecting the same taxonomic uncertainty that surrounds ericymba's validity. As a nominally cenote-endemic form, however, it would warrant a cautious read if it were ever confirmed distinct: the cenotes and groundwater of the Yucatán are increasingly stressed by aquifer extraction, urban and agricultural pollution leaching into the porous limestone, tourism development, and the spread of introduced fishes (including African tilapias and other cichlids) across the peninsula — and a cenote within the city of Mérida itself is about as exposed to urban pressure as a cenote can be. The broader Mayan-cichlid lineage is in no danger — it is abundant, adaptable and even invasive where introduced (notably in Florida) — but any genuinely range-restricted cenote form would be far more vulnerable than its wide-ranging relatives. For now the honest statement is that the taxon is unassessed and its very distinctness unresolved.