How to breed corydoras

Corydoras lay sticky eggs all over the glass and plants, often right after a water change. Bronze, peppered and Venezuelan corys are the easiest to breed. The trick is saving the eggs before the adults and tankmates eat them.

I've bred Venezuelan corys in my own tanks. They're a bright orange-and-black form of the bronze cory, and they breed the same way.

Males and females

Look down on them from above. Females are wider and rounder, especially behind the front fins. Males are slimmer, with slightly more pointed front fins. Keep about two males for every female, in a group of 6 or more. See corydoras care.

Triggering a spawn

• Feed well for a week or two: sinking pellets plus frozen or live bloodworms and brine shrimp. Females should look plump.
• Do a large water change with slightly cooler water, about 3 to 5°F cooler. To corys, it feels like the rainy season.
• Watch for chasing. Males chase the female, then a pair forms a "T": the male holds the female's barbels while she fertilizes a few eggs held between her fins.
• The female sticks the eggs on the glass, plants or decor, and repeats this many times over a few hours.

Saving the eggs

1. Roll the eggs off the glass gently with your finger, or move the plant leaves they're stuck to.
2. Put them in a small container or breeder box of tank water with an air stone for gentle movement.
3. Remove any eggs that turn white and fuzzy each day, so fungus doesn't spread. A tiny amount of methylene blue or an alder cone helps.
4. The eggs hatch in about 3 to 5 days. The fry live off their yolk for another 2 days.

Raising the fry

• First foods: microworms, baby brine shrimp, or finely crushed sinking food.
• Feed small amounts 2 to 3 times a day and siphon out leftovers.
• Bare bottom or fine sand makes it easy to keep clean.
• Clean water matters most. Small daily water changes beat big weekly ones for fry. See how to do a water change.

Fry look like tiny adults after a few weeks and can join a peaceful community tank at about an inch long.

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