Well my good sir, i am going to kinda repeat what i said earlier, but better..
Breeding Corydoras is rewarding and fun, but presents challenges. First obviously you need to get males and females, unless you have a trained eye this can be trickier than thought. It is highly recommended that you get get 3:1 ratio of males to females. Males are the first and easiest to emit spawning behavior. Now i recommend setting up a tank specifically for breeding these fish, it will increase your chances for success greatly. For the spawning tank get at LEAST 10 gallons, the bigger the better but i don't recommend over 55 gallons. Next make sure you filtration is excellent, they need crystal clear water and clean. Sand or no substrate will work, but i have only used sand for breeding. Heavily planted with live plants or fake, and use caves or wood for cover. Leave some spaces open and clear, this is where they will initiate spawning behavior. You will need to let them settle into their new love pad for at least a week, then you will need to start condition feeding them. Live black worms are best, but you might be able to to it off live brine shrimp or freeze dried brine shrimp. Make sure to double their feeding schedule with these new foods, but make sure to alternate foods and not to foul the water. Fouling the water will ruin the whole process, if your corydoras like the food and are becoming conditioned for breeding, which can take varied times, then you will notice the females are going to look rather fat in the abdomen area, these are eggs. Then you will need to initiate spawining, the Corydoras spawn in the food rich rainy season in the amazon, (hence the extra feeding) and you will need to do a 25 to 30% water change with a water replacement temperature change of 4 to 6 degrees lower to recreate the influx of colder waters brought by the rain. Do this crucial step at night so they will spawn at night. If you have done everything right this should initiate spawining, still they might not despite everything seemingly perfect. Good luck with your spawning!
