The short answer
Corydoras are moderately easy to breed. The classic trigger is a large, slightly cooler water change on a well-fed group — it mimics the rainy season and often sets off spawning within a day. The females then lay sticky eggs on the glass, plants and décor. The catch is that adults (and other fish) will eat the eggs, so you usually need to move either the eggs or the parents to raise a batch.
Conditioning and triggering a spawn
Keep a group of at least six, ideally with a couple more males than females, and feed them well on sinking foods, frozen and live treats for a week or two. When they’re plump and active, do a water change of 50% or more using water a few degrees cooler than the tank, with a little extra flow and aeration. Chasing, “T-position” pairing and busy activity along the glass are the signs it worked.
For the species basics, see our bronze corydoras care guide and how many corydoras should I keep together.
Hatching the eggs
The eggs are laid in small clusters and hatch in 3–5 days depending on temperature. To save them:
- Move the eggs — gently roll them off the glass with a finger or blade into a separate hatching container with the same water plus an air stone.
- Or move the adults out and let the eggs hatch where they are.
- Add a drop of methylene blue or an almond leaf to discourage fungus on the eggs.
Raising the fry
Newly hatched corydoras live off their yolk sac for a day or two, then need powdered fry food and, soon after, baby brine shrimp, plus clean water and gentle sponge filtration. See how do I raise fish fry and what do I feed baby fish, our food picks, and browse aquariums for a grow-out tank.