Taxonomy & naming
Geophagus crocatus was described in 2013 by Frances E. Hauser and Hernán López-Fernández, in Zootaxa (volume 3731, issue 2, pages 279–286), from material collected in the Berbice River of east-central Guyana. The holotype (UG/CSBD 1656, originally Royal Ontario Museum 87106, a 6.5 in SL adult) was taken about 14 air-kilometres upstream of Kwakwani at the Mappa Lagoon camp, at roughly 5.17° N, 58.16° W; paratypes are held at the ROM in Toronto. Catalog of Fishes treats the name as valid, and the Guyana freshwater-fish checklist of Taphorn and colleagues (2022) confirms it as an endemic of the Berbice basin. The description brought the number of valid Geophagus species to nineteen and the number known from Guyana to six. The genus Geophagus was erected by Johann Jakob Heckel in 1840, and crocatus sits within Geophagus sensu stricto — the assemblage informally called the 'Geophagus surinamensis group,' diagnosed by Kullander on the synapomorphic caudal ribs that wrap the paired swim-bladder diverticula. Within that group it is distinguished from species outside the complex by its incomplete suborbital (cheek) stripe, formed only by a black mark on the preopercle rather than a full bar running to the eye, and from the species that share that incomplete marking by its unique flank pattern of six bars with bars two and three fusing dorsally between the ninth and tenth dorsal spines. The broader phylogenetic placement of Geophagus among the eartheaters was mapped by López-Fernández, Honeycutt, Stiassny and Winemiller (2005), who recovered Geophagus sensu stricto as sister to 'Geophagus' steindachneri and, in turn, to Gymnogeophagus.
Morphology
Geophagus crocatus is a moderately deep-bodied, fusiform eartheater that reaches about 6.5 in in standard length (roughly 8 in including the tail), with the holotype an adult of 6.5 in SL. Like other true Geophagus it has the steep, blunt-snouted profile and underslung, protrusible mouth of a substrate-sifter. Fin counts run to 17 dorsal spines with 11–12 soft rays, three anal spines with 7–8 soft rays, and 32–33 vertebrae. Coloration in life is a brassy olive-tan, and the trait that gives the fish its name is a saffron- to golden-yellow flush across the operculum (gill cover) of living specimens — the Latin crocatus means 'saffron-coloured.' Two features fix its identity. First, the suborbital marking is incomplete: a black blotch sits on the preopercle but does not extend forward as an unbroken stripe to the eye, unlike relatives such as Geophagus grammepareius, Geophagus taeniopareius, Geophagus argyrostictus, Geophagus gottwaldi and Geophagus harreri. Second, the flank bears six dark vertical bars, and bars two and three slope toward one another and join at the base of the spiny dorsal fin between spines nine and ten — a configuration found in no other member of the genus. This bar count separates it cleanly from congeners with the same incomplete cheek mark: bars are effectively absent in Geophagus proximus and Geophagus brachybranchus, number four in Geophagus winemilleri, and number seven in Geophagus dicrozoster. A dark midlateral blotch, the badge of the genus, sits on the side. No pronounced sexual dimorphism has been documented for the species; as in the surinamensis group generally, sexes are similar in pattern, and any difference is expected to be subtle (males tending to grow somewhat larger and develop slightly extended fin tips), so the sexes are not reliably told apart on external features alone.
Habitat
The species is endemic to the Berbice River drainage of Guyana, in northern South America, where it is the only Geophagus present and occurs both above and below the rapids at Itabru Falls, including the quiet, lake-like expansions below the falls. The IUCN assessment records it from both still and flowing waters — oxbow lakes and flooded savannahs as well as the main channel of the river, its tributaries, creeks and forest streams. FishBase characterises the typical biotope as blackwater running through thick gallery forest, with the fish most abundant in stretches of sluggish current over sandy bottoms where the forest canopy opens up and overhanging cover is sparse. Water chemistry measured where the type series was collected was soft and warm, spanning blackwater conditions: very low conductivity (about 2–39 microsiemens), temperatures of 77–91 °F, and a pH range from distinctly acidic to about neutral (4.1–7.1). These figures place it firmly among the soft-water, warm-water cichlids of the Guiana Shield rivers. The fish forages over the open sandy substrate of these shallow, slow reaches, and the documented habitat is the riverbed and shallow margins rather than any deep-water zone.
Feeding
Geophagus crocatus is a benthic sand-sifter in the classic eartheater mould. Its underslung, protrusible mouth and the well-developed lobe on the gill arch let it take in mouthfuls of sand, sort edible particles — small invertebrates, larvae, detritus and organic matter — against the gill rakers, and expel the cleaned grit through the gill openings and mouth. FishBase places it low on the food web, with an estimated trophic level near 2.3, consistent with a small-prey invertivore and detritivore rather than a predator of other fish. In its native Berbice the species works the sandy bottoms of sluggish blackwater reaches, and this constant winnowing of the substrate makes eartheaters important processors of the soft sediment and leaf-litter zone of the river. Its abundance in open, sandy, sparsely-canopied stretches reflects a foraging strategy built around clean sand it can sift efficiently.
Mating
No courtship or pair-formation behaviour has been described for Geophagus crocatus from the wild — the original description and subsequent surveys treated distribution, morphology and habitat rather than reproduction. What can be said is drawn from the surinamensis group to which it belongs. True Geophagus of this assemblage are generally biparental and form pairs that defend a territory together over open sand; the partners clean a spawning site and share parental duties through the brooding period. Like most cichlids they become territorial around spawning, with the pair driving other fish off the chosen patch of substrate. Whether crocatus shows the same pattern in the Berbice has not been observed and reported, so its social and courtship behaviour is presented here as genus-typical rather than documented for the species itself.
Breeding
The breeding biology of Geophagus crocatus has not been documented, either in the wild or, as far as the literature records, in aquaria. Its membership in Geophagus sensu stricto, the surinamensis group, is informative: the well-studied members of this group — including Geophagus surinamensis itself, Geophagus brachybranchus and Geophagus camopiensis — are biparental, 'delayed' or larvophilous mouthbrooders. In that strategy the pair first spawns onto a cleaned patch of open substrate, the adhesive eggs are guarded and tended on the bottom for a day or two, and only after the eggs hatch does a parent take up the larvae and carry the developing young in the mouth, releasing the free-swimming fry to forage and gathering them back at any disturbance. Clutch sizes for substrate-then-mouthbrooding Geophagus of comparable body size typically run on the order of one to a few hundred eggs, but no count specific to crocatus exists. The honest position is that the species' clutch size, spawning triggers and the duration of parental care are unrecorded; the delayed-mouthbrooding mode is inferred from its close relatives rather than observed in this fish.
In the aquarium
Geophagus crocatus is essentially unknown in the aquarium hobby. It is a Guyanese endemic that has only been described since 2013, it carries no established trade name beyond the scientific one, and it does not appear in the ornamental supply chain in any regular way; the IUCN notes only that it has 'potential' as an aquarium fish. There is therefore no body of first-hand keeping or breeding reports for the species, and any husbandry advice has to be extrapolated from its close, well-kept relatives in the surinamensis group such as Geophagus surinamensis and Geophagus altifrons.
On that basis, the requirements would be those of a medium-large eartheater. A fish of around 6.5 in needs a long tank — on the order of 59 in as a sensible minimum for a small group, and more for a colony — because eartheaters are social, do best in groups of five or more, and need floor space rather than height. The single non-negotiable furnishing is a deep bed of fine, soft sand: the entire feeding apparatus of the fish is built around taking sand into the mouth and sifting it, and gravel both prevents that natural behaviour and risks abrading the gills. Décor should leave open sand to forage over, with driftwood, leaf litter and scattered smooth stones for structure and to break up sightlines.
Water should mirror the soft, warm, acidic-to-neutral blackwater of the Berbice: a temperature in the warm 79–86 °F band, a pH on the acidic side of neutral (the wild range runs 4.1–7.1), and low hardness and conductivity. These are warm-water fish and should not be kept cool. As with all eartheaters, clean water matters — the group is prone to head-and-lateral-line erosion when dissolved wastes accumulate, so generous filtration and large regular water changes are important, while keeping flow gentle to suit a fish of slow, sandy reaches. Diet is straightforward for a sand-sifter: sinking foods that can be worked over the bottom — quality sinking pellets, frozen bloodworm, daphnia and brine shrimp — feed the natural foraging behaviour. Tankmates should be peaceful, soft-water South Americans of similar scale that will not outcompete a deliberate bottom-feeder; like most Geophagus it should be peaceful outside of spawning. None of this has been verified specifically for crocatus, however, and a keeper acquiring wild Guyanese stock would be among the first to document it.
Conservation
The IUCN Red List assesses Geophagus crocatus as Least Concern (assessed 1 November 2023, published 2024, by D.C. Taphorn and D. Rodríguez-Olarte). The population trend is reported as stable. Despite being a single-river endemic, the species is judged not to be at risk at present: it is found through the Berbice drainage in a range of habitats from the main channel to flooded savannahs and forest streams, both above and below Itabru Falls. The assessment lists potential pressures rather than active declines — non-timber agriculture, mining and quarrying, and logging and wood-harvesting in the basin — and notes that the fish is probably taken in small numbers by subsistence fishers and has potential value in the ornamental trade. It carries no CITES or CMS listing. As a narrow-range endemic of one Guiana Shield river, its long-term fate is tied to the integrity of the Berbice basin: a species confined to a single drainage has no refuge elsewhere, so the watershed-scale threats the assessors flag — particularly mining and deforestation, with their attendant sedimentation and water-quality effects — are the variables that would matter most for it, even though none is documented as causing decline today.