First, get the eggs away from the adults
In outline, raising baby corydoras starts before the eggs hatch, because the parents are the first threat to them. A spawning female glues her eggs, carried a few at a time between her pelvic fins, onto the aquarium glass, plant leaves, or the filter. Adults and tank-mates will pick those pale eggs off again as food, so move them promptly. Roll eggs gently off the glass with a fingertip, or snip and move the leaf they sit on, into a small rearing tank or a floating container in the main tank.
Set that nursery up with water from the parents' tank, a gentle airstone or a mature sponge filter running slowly, and no gravel, so you can see the eggs and later the fry clearly. Corydoras eggs are sensitive to fungal attack, which spreads from any egg that has died to its neighbours, so remove eggs that turn solid white and fuzzy while leaving the clear, ambering, fertile ones in peace.
Hatching and the quiet first days
The eggs typically hatch within a few days, faster in warmer water and slower in cooler, and what emerges barely looks like a fish. The fry rest on the bottom living off their yolk sacs, and during this stage they need nothing from you except stable, clean water and to be left alone. Resist the urge to feed a tank of fry that cannot yet eat; uneaten food at this point only fouls the small volume of water they depend on.
Once the yolk sacs are absorbed and the fry begin nosing along the bottom in short darts, food becomes the whole job. Baby corydoras have tiny mouths and a bottom-feeder's instincts, so offer foods that sink and stay small: infusoria and microworms first, then newly hatched brine shrimp and finely powdered fry food as they grow. Several small feeds spread across the day suit them far better than one large one that decays between meals.
Clean water is the growth engine
More fry are lost to water quality than to any shortage of food. A rearing tank holds little water and receives frequent feeding, a recipe for ammonia if waste accumulates. Siphon the bare bottom daily with airline tubing, working slowly around the nearly invisible fry, and replace what you removed with temperature-matched water, a little at a time.
Small, frequent changes beat large, occasional ones at every stage of the first weeks. As the fry grow and their barbels and body shape become recognisable, you can deepen the water, strengthen filtration gently, and begin mixing in crushed adult foods. Growth will be uneven. A few bold fry race ahead while smaller siblings trail, and that spread is normal rather than a sign of failure, though large fry can be moved on sooner to give the runts room.
Moving the youngsters on
Young corydoras are ready to join a community tank or go to new homes once they are large enough not to be eaten by the fish waiting there and are feeding confidently on ordinary foods. Judge that by the mouths of the fish waiting in the receiving tank, not by age. Acclimate them gradually rather than pouring them straight across.
Expect losses along the way, especially in a first attempt. A breeding group of corydoras will spawn again after water changes that imitate rainfall, so each batch teaches the routine a little better. Keep notes on hatch dates and first foods; their pattern turns an outline into your own reliable method.
Daily fry feeding and siphoning are easy tasks to split between two keepers, provided nobody guesses who did them. KinsLe Care Teams lets you assign each day's corydoras fry duties to a named person and see each task checked off with its completion time.