Two-river Cory

Geographic Origin and Biotope: South American species, endemic to the Paraná and São Francisco river basins in Brazil (hence the epithet "difluviatilis", meaning of the two rivers). Frequents clear and moderately fast flowing waters, with mixed sand and pebble bottoms.

Taxonomy and Morphology: Belonging to the Callichthyidae family. Small-sized Corydoras, adult females do not exceed 4.5 cm (1.8 inches). Distinguished from related species by a stocky, rounded snout and the peculiar morphology of the defensive bony plates and pectoral rays.

Social Behavior: Markedly gregarious animal, tireless scavenger. Absolutely requires to be housed in schools of no less than 6 individuals. Extremely lively, incessantly patrols the sandy bottom working as a group.

Coloration and Sexual Dimorphism: Pinkish-beige background, densely covered by a myriad of small irregular brown spots ("freckled pattern"). Totally lacks black bands or masks over the eyes. Females are noticeably more corpulent and round in the ventral profile.

Aquarium Setup: Fine sand bottom mandatory. Replicate a river habitat: smooth rocks and round pebbles, intricate branches to dampen the flow, and strong water movement guaranteed by a circulation pump to saturate the tank with oxygen.

Diet and Feeding: Benthic omnivorous micropredator. The diet must consist of tabs/wafers for carnivorous bottom fish, alternated with appropriately sized live/frozen foods (bloodworms, daphnia, brine shrimp). A diet based on the leftovers of other fish is fatal.

Water Quality: Clean and highly oxygenated water: sensitive to nitrates (keep <20ppm). Classic temperatures between 22 and 26°C (72-79°F). Hardness GH 2-12, slightly acidic or neutral pH (6.0 - 7.2). Weekly partial changes of 20-30% are indispensable.

Compatibility and Tankmates: Strictly peaceful. Excellent member of a river biotope alongside medium-small South American Characins (Hemigrammus, Hyphessobrycon) and rheophilic Loricariids. Avoid cohabitation with digging or aggressive Cichlids that would dominate the bottom.

Aquarium Reproduction: T-position reproductive model: triggered by cold thermal shocks (-3°C) induced via water changes. The eggs (about 40-60) are adhesive and positioned on the glass in high current areas or on smooth rocks. Tendency for cannibalism towards the eggs: move the breeders.

Risks and Diseases: Abrasive gravel will cause barbel consumption and irrecoverable bacterial infections. Very high sensitivity to Copper sulfate, malachite green, and aggressive treatments against ectoparasitic pathologies.