Geophagus dicrozoster

Overview

Geophagus dicrozoster is a social Orinoco sand sifter with a relatively elongated profile and a Y-shaped junction between its fourth and fifth flank bars. Oral brood care begins after hatching, unlike the immediate egg collection practiced by some similar fishes from the same region.

Distribution & habitat

Records cover major Venezuelan Orinoco tributaries, the Casiquiare, and headwaters of the Negro. The available account does not confirm occurrence in Brazil.

Low-mineral acidic blackwater appears to be favored, especially quiet lagoons, although at least one collection came from rapids. Sand or mud is interspersed with wood, rocks, and leaves.

Aquarium setup

Provide at least a 180 by 60 cm footprint for a group. Soft sand allows sifting without the feeding difficulties and injury risks associated with coarse gravel. Subdued light, roots, wood, and flat spawning stones are suitable furnishings.

Heavy leaf accumulation readily becomes suspended debris. Use mature filtration with fine-particle capture, protect pumps from sand, and perform weekly changes of at least 50–70%. Avoid strong direct currents and unstable water chemistry.

Diet & feeding

The genus sifts small invertebrates, seeds, and organic debris from the bottom. Offer fine prepared foods, including plant-containing products, with small bloodworms, tubifex, brine shrimp, and similar fare. Adults still need modest particle sizes. Divide feeding into three or four small portions daily.

Behaviour & compatibility

Keep at least five to eight. Loose groups develop a hierarchy, while too few individuals may remain unsettled or expose weaker fish to persistent harassment. Usually peaceful, it should not share with aggressive territorial bottom dwellers or harder-water species.

Sexual dimorphism

Routine external differences are unreliable. The female ovipositor becomes visible at spawning.

Breeding

Captive reproduction is established, with eggs guarded before larvae enter parental mouths. Allow young fish to pair naturally; maturity requires at least about a year.

Pairs clean and defend rock, wood, or glass. After successive egg batches are fertilized, females tend the eggs as males guard surrounding space. Hatching takes roughly 72 hours, after which oral carrying begins, usually with the female.

Male involvement varies from early shared care or brood exchanges to little participation, and some males take over after excluding the female. At about eight to eleven days of age, fry begin swimming and are released progressively to feed, retreating into mouths when threatened. Fine dry food, brine-shrimp nauplii, and microworms are suitable. Community companions, including conspecifics, pose a predation risk to released young.

Notes

Dark preopercular markings, seven flank bars, and the characteristic Y-shaped connection form useful combined identification features. Trade mislabeling is common, especially among juveniles.