Blue Corydoras

Geographic Origin and Biotope: Coastal rivers of southeastern Brazil (States of Espirito Santo, Rio de Janeiro and Sao Paulo). Inhabits open rivers with cooler currents than the Amazonian average, rich in rounded rocks and sand.

Taxonomy and Morphology: Blue Corydoras (Corydoras nattereri). Species native to subtropical zones, tolerates lower temperatures (down to 20°C / 68°F) and is morphologically classic: torpedo body and well-developed barbels.

Social Behavior: Very calm and absolutely gregarious by nature. Lives only in schools of 6-8 individuals and up. Spends the day sifting and brushing every grain of sand.

Coloration and Sexual Dimorphism: Pale silvery/gray base color. A mighty black stripe stands out clearly (with iridescent green/blue edges depending on the light) running on the flank, crossing the whole body. Females disproportionately wider (more voluminous) than males.

Aquarium Setup: Minimum 80 cm (32 inches) aquarium, unheated if the room is between 20-22°C (68-72°F) (they loathe summers at 29°C (84°F), for which an aerator is needed). Sand bottom is a must. Recreate soft currents with a filter or a circulation pump.

Diet and Feeding: Bottom omnivore specialized in microinvertebrates. Accepts commercial wafers which should be regularly alternated with frozen bloodworms and brine shrimp.

Water Quality: Appreciates excellently oxygenated waters (cool currents). High nitrates are the number one enemy; a putrefying bottom will poison the fish via unstoppable bacteriosis.

Compatibility and Tankmates: Exceptional for "cold" communities (not suitable for Discus tanks). Excellent with small Gymnocorymbus (Black Skirt Tetra), Gymnogeophagus (subtropical cichlids) and cold water Loricariids.

Aquarium Reproduction: Classic corydoras reproduction, abundantly stimulated by a drastic thermal drop (monsoon simulation). Remove the eggs, very adhesive and laid on the glass, before the parents eat them.

Risks and Diseases: Extremely susceptible to heat: if the temperature exceeds 27°C (80°F), the metabolism goes crazy and the fish waste away quickly due to a lack of oxygen on the bottom.