Hello elia.benini.
Welcome to PlanetCatfish, and congratulations on getting the Corydoras concolor - they grow into lovely fishes and the males get impressive fins.
To answer your questions, I recommend that you read the Cat-eLog page for this species (here:
). Scroll down to near the bottom of the page and look for the "Breeding Reports." Click on each of them, especially the first 3 or 4 because they contain a lot of information about how to keep this species, such as water temperature and hardness, food, etc.
Good luck, Eric