About Corydoras Catfish

Corydoras Catfish (often called "Cory Cats" or "Corys") are the perfect bottom-dwelling community fish. These small, armored catfish are peaceful, active, and entertaining to watch as they scavenge the substrate. They are schooling fish that must be kept in groups and are excellent tank cleaners, though they should not be relied upon as the sole cleaning crew. With over 160 species available, there is a Corydoras for every aquarium.

Care Guide

Care Requirements

Tank Setup

Corydoras have specific substrate requirements:

  • Minimum 10 gallons (20+ for most species)
  • Soft, smooth substrate (sand or smooth gravel) - critical for their barbels
  • Gentle filter (avoid strong currents)
  • Heater to maintain 72-78°F
  • Hiding places (caves, driftwood, dense plants)
  • Open areas for foraging

Substrate Warning: Sharp gravel damages their sensitive barbels and mouths. Use sand or very smooth gravel.

Water Quality

  • Temperature: 72-78°F (22-25.5°C)
  • pH: 6.0-7.5 (species-dependent)
  • Water Hardness: Soft to moderate (2-15 dGH)
  • Ammonia/Nitrite: 0 ppm
  • Nitrate: <30 ppm

They prefer well-oxygenated water. Weekly 25% water changes are essential.

Feeding

Corydoras are omnivorous bottom-feeders but need supplemental feeding:

  • Sinking pellets or wafers (designed for bottom feeders)
  • Frozen foods: bloodworms, brine shrimp
  • Live foods: blackworms, grindal worms
  • Vegetables: blanched zucchini, cucumber

Critical: Do not rely on “leftover” food! They need dedicated feeding.

Feeding Schedule: Once daily after lights out or when other fish are finished. Target-feed to ensure they get food.

Behavior & Compatibility

Corydoras are peaceful and compatible with nearly all community fish:

  • Perfect Tank Mates:

    • Small Tetras (Neon, Cardinal, Ember)
    • Rasboras (Harlequin, Chili)
    • Livebearers (Guppies, Platies)
    • Gouramis (Dwarf, Honey)
    • Betta Fish (in larger tanks)
    • Angelfish (in larger tanks)

  • Avoid:

    • Large, aggressive fish (Oscars, large Cichlids)
    • Fin-nippers

Schooling Requirements

Must be kept in groups of 6 minimum, preferably 8-10+:

  • Display natural schooling behavior
  • Feel safer and less stressed
  • More active and entertaining
  • Better coloration

Larger groups also distribute aggression and encourage more confident behavior.

  • Bronze Cory (C. aeneus): 2.5 inches, very hardy, bronze/green color
  • Panda Cory (C. panda): 2 inches, black and white pattern
  • Julii Cory (C. julii): 2 inches, spotted pattern, delicate
  • Sterbai Cory (C. sterbai): 2.5 inches, orange fins, very popular
  • Pygmy Cory (C. pygmaeus): 1 inch, stays tiny, nano tank suitable
  • Adolfo’s Cory: 2 inches, striking orange head

Air Breathing

Corydoras can breathe air!

  • They have a modified intestine for air breathing
  • You’ll see them dart to the surface occasionally
  • This is normal behavior
  • Don’t panic when you see them “gasp” at the surface

Common Health Issues

  1. Barbel Erosion: From sharp substrate; use sand or smooth gravel
  2. Ich: White spots; treat with temperature and medication
  3. Red Blotch Disease: Bacterial infection; treat with antibiotics
  4. Skinny Disease: Internal parasites; treat with anti-parasitic

Breeding

Some species (Bronze, Peppered) are relatively easy to breed:

  • Trigger with large, cool water changes (10°F drop)
  • T-bar mating position (unique to Corydoras)
  • Eggs attached to glass, plants, or substrate
  • Remove eggs to separate hatching tank
  • Feed fry: microworms, baby brine shrimp

Tank Maintenance

  • Weekly 25% water changes
  • Vacuum substrate gently (they forage there)
  • Clean filter media monthly
  • Test water parameters regularly
  • Watch barbel health as indicator of substrate quality

Tips for Success

  • Always use smooth substrate - this is critical
  • Keep in groups of 6 minimum
  • Feed dedicated sinking food daily
  • Provide hiding spots and plants
  • Maintain excellent water quality
  • Choose appropriate species for your tank size
  • Watch for barbel erosion (sign of substrate issues)
  • They’re social - more is better!

Interesting Facts

  • Over 160 recognized species
  • Found throughout South America
  • “Cory” comes from Greek for “helmet” and “doras” for “skin”
  • Can make audible clicking/squeaking sounds
  • Some species are nearly extinct in the wild due to over-collection

Compatible Tank Mates

🐠 Neon Tetra 🐠 Guppy 🐠 Betta Fish 🐠 Angelfish 🐠 Dwarf Gourami 🐠 Harlequin Rasbora