Flagtail Corydoras, Corydoras robineae, is a South American armored catfish native to the Rio Negro system in Brazil and nearby tributaries within the Amazon Basin. It inhabits slow-moving blackwater streams and forest channels with sandy substrates, leaf litter, and submerged wood. These habitats are typically warm, soft, and acidic, with dark tea-colored water created by tannins from decomposing vegetation. Adult Corydoras robineae usually reaches about 2.5 to 3 inches in length and has a noticeably slender, elongated body compared with many Corydoras species. The base coloration is light beige to tan with fine peppering and a subtle darker midline that may be visible along the flank. The most distinctive feature is the caudal fin, which displays bold black banding across a clear to pale background, creating the “flag” pattern that gives the species its common name. The fins are otherwise mostly clear, and the overall patterning is more delicate than the heavier markings seen in many Corydoras. A tank of at least 20 gallons is recommended for a proper group. Flagtail Corydoras are social fish and should be kept in groups of six or more to display natural behavior and reduce stress. A fine sand substrate is strongly recommended so they can sift through the bottom safely without damaging their barbels. The aquarium should include driftwood, leaf litter, and shaded areas while maintaining open sand patches for feeding. Water conditions should be stable and clean. Temperatures between 74 and 80 degrees Fahrenheit are appropriate, with a pH range of roughly 5.5 to 7.0 and soft water preferred. Gentle water movement and good oxygenation are beneficial, and regular water changes help maintain the high water quality these fish prefer. Feeding Flagtail Corydoras is straightforward. In nature they feed on insect larvae, worms, small crustaceans, and organic material sifted from the substrate. In the aquarium they accept sinking pellets, wafers, and frozen foods such as bloodworms, daphnia, and brine shrimp. They should be intentionally fed rather than relied upon as cleanup fish. Temperament is peaceful and social. Corydoras robineae does well with other small to medium peaceful fish that share similar water requirements, including tetras, rasboras, and other gentle species. Aggressive or highly competitive bottom dwellers should be avoided. Breeding Corydoras robineae in captivity is uncommon but possible. Like other Corydoras, they scatter adhesive eggs on plants, glass, or other surfaces. Adults do not guard the eggs and may eat them if left in the breeding tank. Corydoras robineae is a distinctive and less commonly kept Corydoras species valued for its slender form and bold banded tail. When maintained in groups with soft sand substrate and clean, stable water, the Flagtail Corydoras becomes an active and attractive addition to Amazonian community aquariums.
