Graceful Corydoras

Geographic Origin and Biotope: Very rare and elusive. Endemic to the Rio Tapajós and Rio Madeira basins (Brazil). Its specific habitat is the remote clear or black waters marginal to the major rivers, flowing in gallery forests among very dense carpets of leaves, roots, and branches on the bottom.

Taxonomy and Morphology: One of the most "atypical" members of the genus. Presents a markedly slender and filiform morphology (hence "gracilis") compared to the stocky appearance of its cousins. The barbels are also thin. Measures up to 4.5 cm (1.8 inches), but the tubular appearance makes it look even smaller.

Social Behavior: Essential gregariousness. Shy and very reserved species. Avoids open and uncovered areas. Spends the day sneaking into the crevices of the wood or probing the gaps between the dead leaves of the substrate looking for micro-prey.

Coloration and Sexual Dimorphism: Beige-cream background crossed by two very obvious and uninterrupted horizontal black/dark parallel bands along the flanks, making it vaguely resemble an Otocinclus. Mature females do not escape the rule of greater corpulence and ventral width compared to males.

Aquarium Setup: Requires aquariums set up solely for its needs: soft bottom (sand), very little light, dozens of thin roots, and very dense layers of leaves (oak, catappa, alder) in which to "sand" themselves. Fears excessive water movement.

Diet and Feeding: Specialized micropredator, very small mouth. Often refuses classic dry feeds during acclimatization. Provide microgranules or tablets to be crumbled, imperatively and abundantly supplementing with live and frozen Daphnia, Tubifex, and Brine shrimp.

Water Quality: Extremely sensitive to the chemical quality of the water, fatal stagnation of nitrates. Ideal range: 22-26°C (72-79°F). Very soft hardness (GH 2-12) and sub-acidic pH (6.0 - 7.2). Maintenance of the bottom and regular partial changes are life or death for the species.

Compatibility and Tankmates: Given its slender stature and shyness, the ideal is a monospecific tank or with "nano" sized companions: Boraras, small Hyphessobrycon (e.g., amandae), Nannostomus, and dwarf shrimp. Never expose them to medium predators or enormous loricariids.

Aquarium Reproduction: Rare event and among the most difficult for Corydoras. Obtainable in mature tanks simulating intense cold rains with RO water and foraging live food in large quantities. Lays very few and large eggs among mosses (Taxiphyllum). Strict separation for the survival of the young.

Risks and Diseases: Pointy substrate will cause the amputation of the barbels followed by infection and rapid death. Inexperience in feeding or food competition lead these frail fish to silent starvation.