Natural Habitat & Origin
Corydoras are found throughout South America, from Argentina to Trinidad. They inhabit slow-moving rivers, streams, and flooded forests with sandy or muddy bottoms. In the wild, they are found in large schools of dozens to hundreds of individuals.
Popular Species
- Bronze Cory (C. aeneus): The most common and hardiest species. Grows to 2.5 inches.
- Panda Cory (C. panda): White body with black patches over the eyes and tail. Very popular.
- Pygmy Cory (C. pygmaeus): Only grows to 1 inch. Can be kept in smaller tanks (5+ gallons).
- Sterbai Cory (C. sterbai): Beautiful spotted pattern with orange pectoral fins. Tolerates warmer water (up to 84°F), making them ideal for discus tanks.
- Albino Cory: An albino variant of C. aeneus. Same care as bronze corys.
- Julii Cory (C. julii): Spotted pattern. Often confused with the more common C. trilineatus.
Tank Setup
- Tank size: 10 gallons minimum for a group of 6 smaller species. 20+ gallons for larger species.
- Substrate: Fine sand is strongly preferred. Corys constantly sift through substrate with their barbels — rough gravel can damage and erode these sensitive whiskers, leading to infection.
- Hiding spots: Driftwood, caves, and dense plants
- Flow: Moderate — they enjoy some current but don't need powerheads
Water Parameters
- Temperature: 72–79°F (22–26°C) — varies by species
- pH: 6.0–7.5
- Ammonia/Nitrite: 0 ppm
- Nitrate: below 20 ppm
Diet & Feeding
- Staple: Sinking pellets or wafers (Hikari Sinking Wafers, Repashy)
- Supplements: Frozen bloodworms, brine shrimp, daphnia
- Important: Don't rely on leftover food from surface feeders — corys need targeted feeding with sinking foods
Schooling Behavior
Corydoras are highly social and must be kept in groups of at least 6, ideally of the same species. In proper schools, they display entertaining synchronized swimming, foraging together, and even "flashing" to the surface for a gulp of air (this is normal — corys can breathe atmospheric air using a modified intestine).
Tank Mates
Corys are the ultimate community fish — peaceful with virtually everything:
- Tetras, rasboras, livebearers, bettas, gouramis, angelfish
- Other bottom dwellers like kuhli loaches and otocinclus
- Shrimp and snails
Avoid only large, aggressive cichlids that may bully or eat them.
Frequently Asked Questions
Why do my corydoras swim to the surface?
This is completely normal. Corydoras can gulp atmospheric air and absorb oxygen through their intestinal lining. Occasional surface dashes are healthy behavior. If they're doing it constantly, check your water oxygenation.
Can I keep corydoras on gravel?
Fine, smooth gravel is acceptable, but sand is strongly preferred. Sharp gravel will damage their barbels over time, which can lead to infections.