Corydoras robinae

Robine's Cory, also known as the Flagtail Cory, is a dynamic freshwater species originating from the river systems of South America. In its natural habitat, it inhabits areas with a noticeable current, clean water, and a substrate of sand or fine gravel. To provide the best care, an aquarium should replicate these conditions, featuring good water circulation and excellent filtration to maintain high oxygen levels. A soft, sandy substrate is highly recommended, as these fish constantly forage by digging with their delicate barbels; a sharp or coarse substrate can cause injury and infection. Providing ample hiding places with driftwood, caves, and durable plants will help them feel secure.

This is a highly social species that must be kept in schools. A group setting is essential for their well-being, as it encourages natural behavior and reduces stress. In a group, they will display more confidence and activity, often seen darting around the tank in quick, synchronized bursts. While they are bottom-dwellers, they possess the ability to breathe atmospheric air. Periodically, one may be seen making a rapid dash to the surface to gulp air. While this is a natural adaptation, frequent surface breathing could indicate low oxygen levels in the water. As omnivores, their diet should be varied and consist primarily of high-quality sinking foods like pellets and wafers. This should be supplemented with frozen or live foods to ensure a balanced diet. It's important to remember that they are not just 'clean-up crew'; they are active foragers that require their own dedicated feeding. Due to their small size and peaceful but skittish nature, they should be housed with other small to medium-sized, peaceful fish that occupy the middle and upper water columns. Avoid housing them with large, aggressive, or overly boisterous tank mates, which can cause them significant stress and prevent them from feeding.

Corydoras robinae is a validated species within the family Callichthyidae, a group of armored catfishes in the order Siluriformes. Native to freshwater systems in South America, this species is adapted to benthic life in lotic environments characterized by moderate water flow. Its morphology reflects these adaptations, featuring a fusiform (torpedo-shaped) body that is streamlined for navigating currents, along with the characteristic bony plates, or scutes, that provide protection. Ventrally-located barbels are critical sensory organs used for chemoreception, allowing the fish to locate food items like small crustaceans, insect larvae, and detritus within the substrate.

Physiologically, C. robinae exhibits a fascinating respiratory adaptation common to its genus. In addition to primary gill respiration, it is a facultative air-breather, capable of absorbing atmospheric oxygen through its highly vascularized posterior intestine. This allows it to supplement its oxygen supply in hypoxic conditions. Its metabolism is relatively low, contributing to a moderate bioload factor despite its active nature. Ecologically, C. robinae functions as a benthic omnivore and micro-predator. Its foraging behavior, which involves rooting through the substrate, contributes to bioturbation, aerating the top layer of sediment. It also acts as a biofilm consumer, grazing on microorganisms that form on surfaces. The species prefers soft, slightly acidic to neutral water with low concentrations of dissolved solids, typical of many neotropical river systems. While its formal conservation status has not been evaluated by the IUCN, like many ornamental species, its populations are subject to pressures from habitat degradation and collection for the aquarium trade. Further research into its specific ecological role and population dynamics in the wild is warranted.

Successfully breeding Robine's Cory is considered a moderately difficult endeavor that typically requires a dedicated setup and specific environmental triggers. For the highest chance of success, a separate breeding aquarium is recommended. This allows for precise control over water parameters and ensures the safety of the eggs and fry. A higher ratio of males to females, such as two or three males for every one female, is advised to encourage spawning and increase fertilization rates.

Distinguishing between the sexes can be subtle. Generally, mature females that are conditioned for breeding will appear noticeably larger, wider, and more rounded in the abdomen when viewed from above compared to the more slender and typically smaller males. To condition the group for spawning, provide a rich and varied diet consisting of high-protein live and frozen foods for several weeks.

Spawning is often induced by simulating the onset of the rainy season in their natural habitat. This is most effectively achieved by performing a significant water change with water that is a few degrees cooler than the aquarium's current temperature. Increasing water flow at the same time can further stimulate breeding behavior. During the spawning event, the fish will engage in a characteristic 'T-position,' where the male fertilizes a small clutch of eggs held between the female's pelvic fins. The female will then search for a suitable surface, such as the aquarium glass, plant leaves, or a spawning mop, to deposit the adhesive eggs. This process is repeated until all eggs are laid.

Corydoras do not exhibit parental care and will predate on their own eggs. Therefore, it is crucial to either remove the adult fish from the breeding tank or carefully transfer the eggs to a separate, well-aerated hatching container. The fry will hatch after a few days and initially survive by consuming their yolk sac. Once they become free-swimming, they must be fed microscopic foods like infusoria or microworms. As they grow, their diet can be transitioned to baby brine shrimp and finely crushed high-quality flake or pellet food. Maintaining pristine water quality is absolutely critical during these early stages of development.